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                                                                   Exhibit 4.3
                                     Bylaws

                                       of

                                 Mail.com, Inc.

                                    ARTICLE I

                                  STOCKHOLDERS

            Section 1.1. Annual Meetings. An annual meeting of the stockholders
shall be held for the election of directors at such date, time and place either
within or without the State of Delaware as may be designated by the Board of
Directors from time to time. Any other proper business may be transacted at the
annual meeting.

            Section 1.2. Special Meetings. Special meetings of the stockholders
for any purpose or purposes, unless otherwise prescribed by statute or the
certificate of incorporation of the Corporation, may be called at any time by
the Chairman or either Co-Chairman of the Board, as the case may be, the Vice
Chairman of the Board, if any, the President, if any, or the Board of Directors,
to be held at such date, time and place either within or without the State of
Delaware as may be stated in the notice of the meeting. A special meeting of
stockholders shall be called by the Secretary upon the written request, stating
the purpose of the meeting, of stockholders who together own of record a
majority of the outstanding shares of all classes of stock entitled to vote at
such meeting. Business transacted at any special meeting of the stockholders
shall be limited to the purpose or purposes stated in the notice.

            Section 1.3. Notice of Meetings. Whenever stockholders are required
or permitted to take any action at a meeting, a written notice of the meeting
shall be given which shall state the place, date and hour of the meeting, and,
in the case of a special meeting, the purpose or purposes for which the meeting
is called. Unless otherwise provided by law, the written notice of any meeting
shall be given not less than ten nor more than sixty days before the date of the
meeting to each stockholder of record entitled to vote at such meeting. If
mailed, such notice shall be deemed to be given when deposited in the United
States mail, postage prepaid, directed to the stockholder at such stockholder's
address as it appears on the records of the Corporation.

            Section 1.4. Adjournments. Any meeting of stockholders, annual or
special, may be adjourned from time to time, to reconvene at the same or some
other place, and notice need not be given of any such adjourned meeting if the
time and place thereof are announced at the meeting at which the adjournment is
taken. At the adjourned meeting the Corporation may transact any business which
might have been transacted at the original meeting. If the adjournment is for
more than thirty days, or if after the adjournment a new record date is fixed
for the adjourned meeting, a notice of the adjourned meeting shall be given to
each stockholder of record entitled to vote at the meeting.
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            Section 1.5. Quorum. At each meeting of the stockholders, except
where otherwise provided by law or by the certificate of incorporation or these
bylaws, the holders of a majority of the votes of all outstanding shares of
stock entitled to vote on a matter at the meeting, present in person or
represented by proxy, shall constitute a quorum. For purposes of the foregoing,
where a separate vote by class or classes is required for any matter, the
holders of a majority of the votes of all outstanding shares of such class or
classes, present in person or represented by proxy, shall constitute a quorum to
take action with respect to that vote on that matter. Two or more classes or
series of stock shall be considered a single class if the holders thereof are
entitled to vote together as a single class at the meeting. In the absence of a
quorum of the holders of any class of stock entitled to vote on a matter the
holders of such class so present or represented may, by majority vote, adjourn
the meeting of such class from time to time in the manner provided by Section
1.4 of these bylaws until a quorum of such class shall be so present or
represented. Shares of its own capital stock belonging on the record date of the
meeting to the Corporation or to another corporation, of which a majority of the
shares entitled to vote in the election of directors of such other corporation
is held, directly or indirectly, by the Corporation, shall neither be entitled
to vote nor be counted for quorum purposes; provided, however, that the
foregoing shall not limit the right of the Corporation to vote stock, including
but not limited to its own stock, held by it in a fiduciary capacity.

            Section 1.6. Organization. Meetings of the stockholders shall be
presided over by the Chairman or both Co-Chairmen of the Board, as the case may
be, or in the absence of the Chairman or Co-Chairmen of the Board, by the Vice
Chairman of the Board, if any, or, in the absence of the Vice Chairman of the
Board, by the President, or, in the absence of the President by a Vice
President, or, in the absence of the foregoing persons by a chairman designated
by the Board of Directors, or, in the absence of such designation, by a chairman
chosen at the meeting. The Secretary, or in the absence of the Secretary, an
Assistant Secretary shall act as secretary of the meeting, but in the absence of
the Secretary and any Assistant Secretary, the chairman of the meeting may
appoint any person to act as secretary of the meeting.

            Section 1.7. Voting; Proxies. Except as otherwise provided by law or
in the certificate of incorporation, each stockholder entitled to vote at any
meeting of stockholders shall be entitled to one vote for each share of stock
held by such stockholder which has voting power upon the matter in question.
Each stockholder entitled to vote at a meeting of stockholders or to express
consent or dissent to corporate action in writing without a meeting may
authorize another person or persons to act for such stockholder by proxy, but no
such proxy shall be voted or acted upon after three years from its date, unless
the proxy provides for a longer period. A duly executed proxy shall be
irrevocable if it states that it is irrevocable and if, and only as long as, it
is coupled with an interest sufficient in law to support an irrevocable power,
regardless of whether the interest with which it is coupled is an interest in
the stock itself or any interest in the Corporation generally. A stockholder may
revoke any proxy which is not irrevocable by attending the meeting and voting in
person or by filing an instrument in writing revoking the proxy or another duly
executed proxy bearing a later date with the Secretary of the Corporation.
Voting at meetings of the stockholders need not be by written ballot and need
not be conducted by inspectors unless the holders of a majority of the votes of
all outstanding shares of all classes of stock entitled to vote thereon present
in person or represented by proxy at such meeting shall so determine. On a vote
by ballot, each ballot shall be signed by the stockholder voting, or by his

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proxy, if there be such proxy, and shall state the number of shares voted.
Directors shall be elected by a plurality of the votes of the shares present in
person or represented by proxy at the meeting and entitled to vote on the
election of directors. In all other matters, unless otherwise provided by law or
by the certificate of incorporation or these bylaws, the affirmative vote of the
holders of a majority of the votes of the shares present in person or
represented by proxy at the meeting and entitled to vote on the subject matter
shall be the act of the stockholders.

            Section 1.8. Fixing Date for Determination of Stockholders of
Record. In order that the Corporation may determine the stockholders entitled to
notice of or to vote at any meeting of the stockholders or any adjournment
thereof, the Board of Directors may fix a record date, which record date shall
not precede the date upon which the resolution fixing the record date is adopted
by the Board of Directors, and which record date shall not be more than sixty
nor less than ten days before the date of such meeting. If no record date is
fixed by the Board of Directors, the record date for determining stockholders
entitled to notice of or to vote at a meeting of stockholders shall be at the
close of business on the day next preceding the day on which notice is given, or
if notice is waived, at the close of business on the day next preceding the day
on which the meeting is held. A determination of stockholders of record entitled
to notice of or to vote at a meeting of stockholders shall apply to any
adjournment of the meeting; provided, however, that the Board of Directors may
fix a new record date for the adjourned meeting.

            In order that the Corporation may determine the stockholders
entitled to consent to corporate action in writing without a meeting, the Board
of Directors may fix a record date, which record date shall not precede the date
upon which the resolution fixing the record date is adopted by the Board of
Directors, and which date shall not be more than ten days after the date upon
which the resolution fixing the record date is adopted by the Board of
Directors. If no record date has been fixed by the Board of Directors, the
record date for determining stockholders entitled to consent to corporate action
in writing without a meeting, when no prior action by the Board of Directors is
required by law, shall be the first date on which a signed written consent
setting forth the action taken or proposed to be taken is delivered to the
Corporation by delivery to (a) its registered office in the State of Delaware,
(b) its principal place of business, or (c) an officer or agent of the
Corporation having custody of the book in which proceedings of meetings of
stockholders are recorded. Delivery made to the Corporation's registered office
shall be by hand or by certified or registered mail, return receipt requested.
If no record date has been fixed by the Board of Directors and prior action by
the Board of Directors is required by law, the record date for determining
stockholders entitled to consent to corporate action in writing without a
meeting shall be at the close of business on the day on which the Board of
Directors adopts the resolution taking such prior action.

            In order that the Corporation may determine the stockholders
entitled to receive payment of any dividend or other distribution or allotment
of any rights or the stockholders entitled to exercise any rights in respect of
any change, conversion or exchange of stock, or for the purpose of any other
lawful action, the Board of Directors may fix a record date, which record date
shall not precede the date upon which the resolution fixing the record date is
adopted, and which record date shall not be more than sixty days prior to such
action. If no record date is fixed, the record date for determining stockholders
for any such purpose shall be at the close of business on the day on which the
Board of Directors adopts the resolution relating thereto.

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            Section 1.9. List of Stockholders Entitled to Vote. The Secretary
shall prepare and make, at least ten days before every meeting of stockholders,
a complete list of the stockholders entitled to vote at the meeting, arranged in
alphabetical order, and showing the address of each stockholder and the number
of shares registered in the name of each stockholder. Such list shall be open to
the examination of any stockholder, for any purpose germane to the meeting,
during ordinary business hours, for a period of at least ten days prior to the
meeting, either at a place within the city where the meeting is to be held,
which place shall be specified in the notice of the meeting, or, if not so
specified, at the place where the meeting is to be held. The list shall also be
produced and kept at the time and place of the meeting during the whole time
thereof and may be inspected by any stockholder who is present.

            Section 1.10. Consent of Stockholders in Lieu of Meeting. Any action
which may be taken at a meeting of the stockholders may be taken without a
meeting, without prior notice and without a vote, if a consent in writing,
setting forth the actions so taken, shall be signed by the holders of
outstanding stock having not less than the minimum number of votes that would be
required to authorize or take such action at a meeting at which all shares
entitled to vote thereon were present and voted. Prompt notice of the taking of
the corporate action without a meeting by less than unanimous written consent
shall be given to those stockholders who have not consented in writing.

                                   ARTICLE II

                               BOARD OF DIRECTORS

            Section 2.1. Powers; Number; Qualifications. The business and
affairs of the Corporation shall be managed by or under the direction of the
Board of Directors, except as may be otherwise provided by law or in the
certificate of incorporation. The Board of Directors shall consist of eight (8)
members. The number of the Board of Directors may be increased or decreased from
time to time by the affirmative vote of a majority of the entire Board of
Directors.

            Section 2.2. Election; Term of Office; Resignation; Removal;
Vacancies. Except as otherwise provided by statute or these bylaws, the
directors (other than members of the initial Board of Directors) shall be
elected at the annual meeting of stockholders. Each director shall hold office
until his or her successor is elected and qualified or until his or her earlier
resignation or removal. Any director may resign at any time upon written notice
to the Board of Directors or to the President or the Secretary of the
Corporation. Such resignation shall take effect at the time specified therein,
and unless otherwise specified therein no acceptance of such resignation shall
be necessary to make it effective. Any director or the entire Board of Directors
may be removed, with cause, by the holders of a majority of the votes of all
outstanding shares then entitled to vote at an election of directors. Unless
otherwise provided in the certificate of incorporation or these bylaws,
vacancies and newly created directorships resulting from any increase in the
authorized number of directors or from any other cause may be filled by a
majority of the directors then in

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office, although less than a quorum, or by the sole remaining director or by the
stockholders at the next annual meeting thereof or at a special meeting thereof.

            Section 2.3. Regular Meetings. Regular meetings of the Board of
Directors may be held at such places within or without the State of Delaware and
at such times as the Board may from time to time determine, and if so determined
notice thereof need not be given.

            Section 2.4. Special Meetings. Special meetings of the Board of
Directors may be held at any time or place within or without the State of
Delaware whenever called by the Chairman or either Co-Chairman of the Board, as
the case may be, by the Vice Chairman of the Board, if any, by the President, if
any, or by any two directors. Reasonable notice thereof shall be given by the
person or persons calling the meeting.

            Section 2.5. Participation in Meetings by Conference Telephone
Permitted. Unless otherwise restricted by the certificate of incorporation or
these bylaws, members of the Board of Directors, or any committee designated by
the Board, may participate in a meeting of the Board or of such committee, as
the case may be, by means of conference telephone or similar communications
equipment by means of which all persons participating in the meeting can hear
each other, and participation in a meeting pursuant to this bylaw shall
constitute presence in person at such meeting.

            Section 2.6. Quorum; Vote Required for Action. At all meetings of
the Board of Directors, a majority of the entire Board shall constitute a quorum
for the transaction of business. The vote of a majority of the directors present
at a meeting at which a quorum is present shall be the act of the Board unless
the certificate of incorporation or these bylaws shall require a vote of a
greater number. In case at any meeting of the Board a quorum is not present, the
members of the Board present may adjourn the meeting from time to time until a
quorum shall be present.

            Section 2.7. Organization. Meetings of the Board of Directors shall
be presided over by the Chairman or jointly by Co-Chairmen of the Board, as the
case may be, or in the absence of the Chairman or both Chairmen of the Board by
the Vice Chairman of the Board, if any, or in the absence of the Vice Chairman
of the Board by the President, if any, or in their absence by a chairman chosen
at the meeting. The Secretary, or in the absence of the Secretary an Assistant
Secretary, shall act as secretary of the meeting, but in the absence of the
Secretary and any Assistant Secretary the chairman of the meeting may appoint
any person to act as secretary of the meeting.

            Section 2.8. Action by Directors Without a Meeting. Unless otherwise
restricted by the certificate of incorporation or these bylaws, any action
required or permitted to be taken at any meeting of the Board of Directors, or
of any committee thereof, may be taken without a meeting if all members of the
Board or of such committee, as the case may be, consent thereto in writing, and
the writing or writings are filed with the minutes of proceedings of the Board
or committee, as the case may be.

            Section 2.9. Compensation of Directors. Unless otherwise restricted
by the certificate of incorporation or these bylaws, the Board of Directors
shall have the authority to fix the

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compensation of directors. All directors shall receive their reasonable
expenses, if any, of attendance at meetings of the Board of Directors or any
committee thereof. Any director may serve the Corporation in any other capacity
and receive proper compensation therefor.

                                   ARTICLE III

                                   COMMITTEES

            Section 3.1. Committees. The Board of Directors may, by resolution
adopted by a majority of the total number of directors, designate one or more
committees, each to consist of two or more of the directors of the Corporation,
which, to the extent provided in the resolution, may exercise the powers of the
Board of Directors in the management of the business and affairs of the
Corporation. The Board of Directors may designate one or more directors as
alternate members of any committee, who may replace any absent or disqualified
member at any meeting of the committee. Such committee or committees shall have
such name or names as may be determined by the resolution adopted by the
directors. The committees shall keep regular minutes of their proceedings and
report the same to the Board of Directors when required.

            Section 3.2. Committee Rules. Unless the Board of Directors
otherwise provides, each committee designated by the Board may adopt, amend and
repeal rules for the conduct of its business. In the absence of a provision by
the Board or a provision in the rules of such committee to the contrary, a
majority of the entire authorized number of members of such committee shall
constitute a quorum for the transaction of business, the vote of a majority of
the members present at a meeting at the time of such vote if a quorum is the
present shall be the act of such committee, and in other respects each committee
shall conduct its business in the same manner as the Board conducts its business
pursuant to Article II of these bylaws.

                                   ARTICLE IV

                                    OFFICERS

            Section 4.1. Officers; Election. The officers shall consist of at
least a Chairman or Co-Chairmen of the Board of Directors and a Secretary. As
soon as practicable after the annual meeting of stockholders in each year, the
Board of Directors shall elect a Chairman or Co-Chairmen of the Board of
Directors and a Secretary. The Board may also, if it so determines, elect as
officers of the Corporation a Vice Chairman of the Board, a President, one or
more Vice Presidents, one or more Assistant Vice Presidents, one or more
Assistant Secretaries, a Treasurer and one or more Assistant Treasurers and such
other officers as the Board, as the case may be, may deem desirable or
appropriate and may give any of them such further designations or alternate
titles as it considers desirable. Any number of offices may be held by the same
person unless the certificate of incorporation or these bylaws otherwise
provide.

            Section 4.2. Term of Office; Resignation; Removal; Vacancies. Unless
otherwise provided in the resolution of the Board of Directors electing any
officer, each officer shall hold

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office until his or her successor is elected and qualified or until his or her
earlier resignation or removal. Any officer may resign at any time upon written
notice to the Board or to the Chairman or Co-Chairmen of the Board, as the case
may be, or the Secretary of the Corporation. Such resignation shall take effect
at the time specified therein, and unless otherwise specified therein no
acceptance of such resignation shall be necessary to make it effective. The
Board may remove any officer with or without cause at any time by a majority
vote of the total number of directors. Any such removal shall be without
prejudice to the contractual rights of such officer, if any, with the
Corporation, but the election of an officer shall not of itself create
contractual rights. Any vacancy occurring in any office of the Corporation by
death, resignation, removal or otherwise may be filled for the unexpired term by
the Board at any regular or special meeting.

            Section 4.3. Chairman of The Board. The Chairman or Co-Chairmen of
the Board, as the case may be, shall preside at all meetings of the Board of
Directors and of the stockholders at which he, she or they shall be present. In
the absence of one Co-Chairman, the other Co-Chairman shall preside at such
meetings, but if both are present they shall jointly preside at such meetings.
The Chairman or the Co-Chairmen of the Board, as the case may be, shall be the
chief executive officer[s] and, subject to the direction of the Board, shall
have general charge and supervision of the business of the Corporation and, in
general, shall perform all duties incident to the office of Chairman of a
corporation and such other duties as may, from time to time, be assigned to him,
her or them by the Board or as may be provided by law. Co-Chairmen shall have
equal power and authority in their office, unless otherwise provided in these
bylaws or by a resolution of the Board of Directors.

            Section 4.4. Vice Chairman of The Board. In the absence of the
Chairman or both Co-Chairmen of the Board, as the case may be, the Vice Chairman
of the Board, if any, shall preside at all meetings of the Board of Directors
and of the stockholders at which he or she shall be present and shall have and
may exercise such powers as may, from time to time, be assigned to him or her by
the Board or as may be provided by law.

            Section 4.5. President. In the absence of the Chairman or both
Co-Chairmen of the Board, as the case may be, and Vice Chairman of the Board,
the President, if any, shall preside at all meetings of the Board of Directors
and of the stockholders at which he or she shall be present and shall have and
may exercise such powers as may from time to time be assigned to him or her by
the Board or as may be provided by law.

            Section 4.6. Vice Presidents. The Vice President or Vice Presidents,
at the request or in the absence of the President or during the President's
inability to act, shall perform the duties of the President, and when so acting
shall have the powers of the President. If there be more than one Vice
President, the Board of Directors may determine which one or more of the Vice
Presidents shall perform such other duties as may, from time to time, be
assigned to him or her by them by the Board or the President or as may be
provided by law.

            Section 4.7. Secretary. The Secretary shall have the duty to record
the proceedings of the meetings of the stockholders, the Board of Directors and
any committees in a book to be kept for that purpose, shall see that all notices
are duly given in accordance with the provisions of these bylaws or as required
by law, shall be custodian of the records of the Corporation, may

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affix the corporate seal to any document the execution of which, on behalf of
the Corporation, is duly authorized, and when so affixed may attest the same,
and, in general, shall perform all duties incident to the office of secretary of
a corporation and such other duties as may, from time to time, be assigned to
him or her by the Board or the Chairman or Co-Chairmen of the Board of
Directors, as the case may be, or as may be provided by law.

            Section 4.8. Treasurer. The Treasurer shall have charge of and be
responsible for all funds, securities, receipts and disbursements of the
Corporation and shall deposit or cause to be deposited, in the name of the
Corporation, all moneys or other valuable effects in such banks, trust companies
or other depositories as shall, from time to time, be selected by or under
authority of the Board of Directors. If required by the Board, the Treasurer
shall give a bond for the faithful discharge of his or her duties, with such
surety or sureties as the Board may determine. The Treasurer shall keep or cause
to be kept full and accurate records of all receipts and disbursements in books
of the Corporation, shall render to the Chairman or Co-Chairmen of the Board, as
the case may be, and to the Board, whenever requested, an account of the
financial condition of the Corporation, and, in general, shall perform all the
duties incident to the office of treasurer of a corporation and such other
duties as may, from time to time, be assigned to him or her by the Board or the
Chairman or Co-Chairmen of the Board of Directors, as the case may be, or as may
be provided by law.

            Section 4.9. Other Officers. The other officers, if any, of the
Corporation shall have such powers and duties in the management of the
Corporation as shall be stated in a resolution of the Board of Directors which
is not inconsistent with these bylaws and, to the extent not so stated, as
generally pertain to their respective offices, subject to the control of the
Board. The Board may require any officer, agent or employee to give security for
the faithful performance of his or her duties.

            Section 4.10. Compensation. The compensation of the officers of the
Corporation for their services as such officers shall be fixed from time to time
by the Board of Directors. An officer of the Corporation shall not be prevented
from receiving compensation by reason of the fact that he or she is also a
director of the Corporation.

                                    ARTICLE V

                                      STOCK

            Section 5.1. Certificates. Every holder of stock in the Corporation
shall be entitled to have a certificate signed by or in the name of the
Corporation by the Chairman or either of the Co-Chairmen, as the case may be, or
Vice Chairman of the Board of Directors, if any, or the President or a Vice
President, and by the Treasurer or an Assistant Treasurer, or the Secretary or
an Assistant Secretary, of the Corporation, representing the number of shares of
stock in the Corporation owned by such holder. For purposes of Section 158 of
the Corporation Law of the State of Delaware or any other provision of law, the
signature of either Co-Chairman of the Board of Directors shall constitute the
signature of "the Chairman" as provided for therein, unless otherwise prohibited
by law, the certificate of incorporation or these bylaws.

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            There shall be set forth on the face or back of the certificate a
statement referencing the restrictions on transfer of the certificates and
stating that the attempted transfer in violation of such restrictions shall not
be registered on the books of the Corporation.

            If the Corporation is authorized to issue more than one class of
stock or more than one series of any class, the powers, designations,
preferences and relative, participating, option or other special rights of each
class of stock or series thereof and the qualifications of restrictions of such
preferences and/or rights shall be set forth in full or summarized on the face
or back of the certificate which the Corporation shall issue to represent such
class or series of stock, provided that, except as otherwise provided by law, in
lieu of the foregoing requirements, there may be set forth on the face or back
of the certificate which the Corporation shall issue to represent such class or
series of stock a statement that the Corporation will furnish without charge to
each stockholder who so requests the powers, designations, preferences and
relative, participating, optional or other special rights of each class of stock
or series thereof and the qualifications, limitations or restrictions of such
preferences and/or rights.

            Section 5.2. Lost, Stolen or Destroyed Stock Certificates; Issuance
of New Certificates. The Corporation may issue a new certificate of stock in the
place of any certificate theretofore issued by it, alleged to have been lost,
stolen or destroyed, and the Corporation may require the owner of the lost,
stolen or destroyed certificate, or such owner's legal representative, to give
the Corporation a bond sufficient to indemnify it against any claim that may be
made against it on account of the alleged loss, theft or destruction of any such
certificate or the issuance of such new certificate.

            Section 5.3. Transfer of Stock. Upon surrender to the Corporation or
the transfer agent of the Corporation of a certificate for shares duly endorsed
or accompanied by proper evidence of succession, assignment or authority to
transfer, it shall be the duty of the Corporation to issue a new certificate to
the person entitled thereto, cancel the old certificate and record the
transaction upon its records; provided, however, that the Corporation shall be
entitled to recognize and enforce any lawful restriction on transfer. Whenever
any transfer of stock shall be made for collateral security, and not absolutely,
it shall be so expressed in the entry of transfer if, when the certificates are
presented to the Corporation for transfer, both the transferor and the
transferee request the Corporation to do so.

            Section 5.4. Transfer Agents and Registrars. The Board of Directors
may appoint, or authorize any officer or officers to appoint, one or more
transfer agents and one or more registrars.

            Section 5.5. Registered Stockholders. The Corporation shall be
entitled to recognize the exclusive right of a person registered on its records
as the owner of shares of stock to receive dividends and to vote as such owner,
shall be entitled to hold liable for calls and assessments a person registered
on its records as the owner of shares of stock, and shall not be bound to
recognize any equitable or other claim to or interest in such share or shares of
stock on the part of any other person, whether or not it shall have express or
other notice thereof, except as otherwise provided by the laws of Delaware.

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                                   ARTICLE VI

                                  MISCELLANEOUS

            Section 6.1. Registered Office. The registered office of the
Corporation within the State of Delaware shall be in the City of Wilmington,
County of New Castle.

            Section 6.2. Other Offices. The Corporation may also have an office
or offices other than said registered office at such place or places, either
within or without the State of Delaware, as the Board of Directors shall from
time to time determine or the business of the Corporation may require.

            Section 6.3. Fiscal Year. The fiscal year of the Corporation shall
be determined by the Board of Directors.

            Section 6.4. Seal. The Corporation may have a corporate seal which
shall have the name of the Corporation inscribed thereon and shall be in such
form as may be approved from time to time by the Board of Directors. The
corporate seal may be used by causing it or a facsimile thereof to be impressed
or affixed or in any other manner reproduced.

            Section 6.5. Waiver of Notice of Meetings of Stockholders, Directors
and Committees. Whenever notice is required to be given by law or under any
provision of the certificate of incorporation or these bylaws, a written waiver
thereof, signed by the person entitled to notice, whether before or after the
time stated therein, shall be deemed equivalent to notice. Attendance of a
person at a meeting shall constitute a waiver of notice of such meeting, except
when the person attends a meeting for the express purpose of objecting, at the
beginning of the meeting, to the transaction of any business because the meeting
is not lawfully called or convened. Neither the business to be transacted at,
nor the purpose of, any regular or special meeting of the stockholders,
directors or members of a committee of directors need be specified in any
written waiver of notice unless so required by the certificate of incorporation
or these bylaws.

            Section 6.6. Indemnification of Directors, Officers and Employees.
The Corporation shall indemnify such persons for such liabilities in such
manner, under such circumstances and to such extent as permitted by Section 145
of the Delaware General Corporation Law, as now enacted or hereafter amended.
The Board of Directors may authorize the purchase and maintenance of insurance
and/or the execution of individual agreements for the purpose of such
indemnification, and the Corporation shall advance all reasonable costs and
expenses (including attorney's fees) incurred in defending any action, suit or
proceeding to all persons entitled to indemnification under this section 6.6,
all in the manner, under the circumstances and to the extent permitted by
Section 145 of the Delaware General Corporation Law, as now enacted or hereafter
amended.

            Section 6.7. Interested Directors; Quorum. No contract or
transaction between the Corporation and one or more of its directors or
officers, or between the Corporation and any

                                       10
<PAGE>   11

other corporation, partnership, association or other organization in which one
or more of its directors or officers are directors or officers, or have a
financial interest, shall be void or voidable solely for this reason, or solely
because the director or officer is present at or participates in the meeting of
the Board of Directors or committee thereof which authorizes the contract or
transaction, or solely because his or her or their votes are counted for such
purpose, if: (1) the material facts as to his or her relationship or interest
and as to the contract or transaction are disclosed or are known to the Board or
the committee, and the Board or committee in good faith authorizes the contract
or transaction by the affirmative votes of a majority of the disinterested
directors, even though the disinterested directors be less than a quorum; or (2)
the material facts as to his or her relationship or interest and as to the
contract or transaction are disclosed or are known to the stockholders entitled
to vote thereon, and the contract or transaction is specifically approved in
good faith by vote of the stockholders or (3) the contract or transaction is
fair as to the Corporation as of the time it is authorized, approved or
ratified, by the Board, a committee thereof or the stockholders. Common or
interested directors may be counted in determining the presence of a quorum at a
meeting of the Board of Directors or of a committee which authorizes the
contract or transaction.

            Section 6.8. Form of Records. Any records maintained by the
Corporation in the regular course of its business, including its stock ledger,
books of accounts and minute books, may be kept in, or be in the form of, punch
cards, magnetic tape, photographs, microphotographs or any other information
storage device, provided that the records so kept can be converted into clearly
legible form within a reasonable time. The Corporation shall so convert any
records so kept upon the request of any person entitled to inspect the same.

            Section 6.9. Dividends. Subject to the provisions of law and the
certificate of incorporation, dividends upon the shares of capital stock of the
Corporation may be declared by the Board of Directors at any regular or special,
meeting. Dividends may be paid in cash, in property or in shares of stock of the
Corporation, unless otherwise provided by statute or the certificate of
incorporation.

            Section 6.10. Reserves. Before payment of any dividend, there may be
set aside out of any funds of the Corporation available for dividends such sum
or sums as the Board of Directors may, from time to time, in its absolute
discretion, think proper as a reserve or reserves to meet contingencies, or for
equalizing dividends, or for repair or maintaining any property of the
Corporation or for such other purpose as the Board of Directors may think
conducive to the interests of the Corporation. The Board of Directors may modify
or abolish any such reserves in the manner in which it was created.

            Section 6.11. Checks, Notes, Drafts, Etc. All checks, notes, drafts
or other orders for the payment of money of the Corporation shall be signed,
endorsed or accepted in the name of the Corporation by such officer, officers,
person or persons as from time to time may be designated by the Board of
Directors or by an officer or officers authorized by the Board of Directors to
make such designation.

            Section 6.12. Execution of Contracts, Deeds, Etc. The Board of
Directors may authorize any officer or officers, agent or agents, in the name
and on behalf of the Corporation to enter into

                                       11
<PAGE>   12

or execute and deliver any and all deeds, bonds, mortgages, contracts and other
obligations or instruments, and such authority may be general or confined to
specific-instances.

            Section 6.13. Voting of Stock in Other Corporations. Unless
otherwise provided by resolution of the Board of Directors, the Chairman or
either Co-Chairman of the Board, as the case may be, from time to time, may (or
may appoint one or more attorneys or agents to) cast the votes which the
Corporation may be entitled to cast as a shareholder or otherwise in any other
corporation, any of whose shares or securities may be held by the Corporation,
at meetings of the holders of the shares or other securities of such other
corporation. In the event one or more attorneys or agents are appointed, the
Chairman or Co-Chairmen of the Board, as the case may be, may instruct the
person or persons so appointed as to the manner of casting such votes or giving
such consent. The Chairman or Co-Chairmen of the Board, as the case may be, may,
or may instruct the attorneys or agents appointed to, execute or cause to be
executed in the name and on behalf of the Corporation and under its seal or
otherwise, such written proxies, consents, waivers or other instruments as may
be necessary or proper in the circumstances.

            Section 6.14. Amendment of Bylaws. These bylaws may be amended or
repealed by a vote of the majority of the total number of directors or a vote of
the stockholders by a majority of the votes of all outstanding shares of stock
entitled to vote in a general election of directors.

Dated as of March 14, 2000.

                                       12<PAGE>   1

                                                                    EXHIBIT 10.1

                                 MAIL.COM, INC.
                             2000 STOCK OPTION PLAN

1. PURPOSE.

     The purpose of the Mail.com, Inc. 2000 Stock Option Plan (the "Plan") is to
provide for the grant of stock options as an incentive to selected directors,
officers, employees and consultants of Mail.com, Inc. (the "Company") and any
Subsidiary of the Company, to acquire a proprietary interest in the Company, to
continue as directors, officers, employees and consultants and to increase their
efforts on behalf of the Company.

2. DEFINITIONS.

     As used in the Plan, the following terms shall have the meanings set forth
below:

          (a) "Board " shall mean the Board of Directors of the Company.

          (b) "Code" shall mean the Internal Revenue Code of 1986, as amended
     from time to time, and any regulations promulgated thereunder.

          (c) "Committee" shall mean the committee described in Section 3.

          (d) "Company" shall mean Mail.com, Inc., a Delaware corporation, and
     any successor corporation.

          (e) "Exchange Act" shall mean the Securities Exchange Act of 1934, as
     amended.

          (f) "Fair Market Value" means, as of any date, the value of Stock or
     other property determined as follows:

             (i)   If the Stock is listed on any established stock exchange or a
        national market system, including without limitation the Nasdaq National
        Market or The Nasdaq SmallCap Market of The Nasdaq Stock Market, its
        Fair Market Value shall be the closing sales price for such Stock (or
        the closing bid, if no sales were reported) as quoted on such exchange
        or system for the last market trading day prior to the time of
        determination, as reported in The Wall Street Journal or such other
        source as the Committee deems reliable;

             (ii)  If the Stock is regularly quoted by a recognized securities
        dealer but selling prices are not reported, its Fair Market Value shall
        be the mean between the high bid and low asked prices for the Stock for
        the last market trading day prior to the time of determination; or

             (iii) In the absence of an established market for the Stock, or if
        Fair Market Value is in reference to property other than Stock, the Fair
        Market Value thereof shall be determined in good faith by the Committee.

          (g) "Grantee" shall mean an officer, director, employee or consultant
     of the Company to whom an Option has been granted under the terms of the
     Plan.

          (h) "Incentive Stock Option" shall mean an option granted under the
     Plan that is intended to meet the requirements of Section 422 of the Code
     or any successor provision.

          (i) "Nonemployee Director" shall mean a director of the Company who is
     a "nonemployee director" within the meaning of Rule 16b-3.

          (j) "Non-Qualified Stock Option" shall mean an option granted under
     the Plan that is not intended to be an Incentive Stock Option.

          (k) "Option" shall mean an Incentive Stock Option or a Non-Qualified
     Stock Option.

<PAGE>   2

          (l) "Option Agreement" shall mean a written agreement between the
     Company and a Grantee as described in Section 6.

          (m) "Outside Director" shall mean a director of the Company who is an
     "outside director" within the meaning of Section 162(m) of the Code.

          (n) "Plan" shall mean this Mail.com, Inc. 2000 Stock Option Plan, as
     amended from time to time.

          (o) "Rule 16b-3" shall mean Rule 16b-3 promulgated by the Securities
     and Exchange Commission under the Securities Exchange Act of 1934, as
     amended, or any successor rule or regulation.

          (p) "Stock" shall mean shares of Class A Common Stock, $.01 par value,
     of the Company or such other securities or property as may become subject
     to Options pursuant to an adjustment made under Section 8.

          (q) "Subsidiary" shall mean any corporation (other than the Company)
     in an unbroken chain of corporations beginning with the Company if each of
     the corporations other than the last corporation in the unbroken chain owns
     more than 50% of the total combined voting power of all classes of stock in
     one of the other corporations in such chain.

3. ADMINISTRATION.

     (a) The Plan shall be administered by a committee (the "Committee")
designated by the Board. The Committee shall consist of at least two directors
and may consist of the entire Board; provided, however, that (i) if the
Committee consists of less than the entire Board, each member shall be a
Nonemployee Director and (ii) to the extent necessary for an Option intended to
qualify as performance-based compensation under Section 162(m) of the Code to so
qualify, each member of the Committee shall be an Outside Director.

     (b) The Committee shall have plenary authority in its discretion, subject
only to the express provisions of the Plan and, in reference to the Incentive
Stock Options, to Code Section 422:

          (i)   to select the Grantees, the number of shares of Stock subject to
     each Option and terms of the Option granted to each Grantee (including
     without limitation the period during which such Option can be exercised and
     any restrictions on exercise), provided that, in making its determination,
     the Committee shall consider the position and responsibilities of the
     individual, the nature and value to the Company of his or her services and
     accomplishments, the individual's present and potential contribution to the
     success of the Company and any other factors that the Committee may deem
     relevant;

          (ii)  to determine the dates of the Option grants;

          (iii) to prescribe the form of the Option Agreements;

          (iv)  to adopt, amend and rescind rules and regulations for the
     administration of the Plan and for its own acts and proceedings;

          (v)   to decide all questions and settle all controversies and
     disputes of general applicability that may arise in connection with the
     Plan; and

          (vi)  to modify or amend any outstanding Option as provided in Section
     7(h).

All decisions, determinations and interpretations with respect to the foregoing
matters shall be made by the Committee and shall be final and binding upon all
persons.

     (c) DELEGATION.  The Committee may delegate authority to an officer of the
Company to grant Options to Grantees who are not subject to the short-swing
profit rules of Section 16 of the Exchange Act and are not "covered employees"
whose compensation is subject to the deduction limit of Section 162(m) of the
Code, at the discretion of such appointed officer, provided, however, that the
appointed officer shall have no authority to grant Options in units greater than
80,000 without approval of the Committee.

     (d) EXCULPATION.  No member of the Board or Committee shall be personally
liable for monetary damages for any action taken or any failure to take any
action in connection with the administration of the

                                       2
<PAGE>   3

Plan or the granting of Options under it unless such action or failure to take
action constitutes self-dealing, willful misconduct or recklessness; provided,
however, that the provisions of this subsection shall not apply to the
responsibility or liability of a director pursuant to any criminal statute or to
the liability of a director for the payment of taxes pursuant to local, state or
federal law.

     (e) INDEMNIFICATION.  Each member of the Board or Committee shall be
entitled without further act on his part or her part to indemnity from the
Company to the fullest extent provided by applicable law and the Company's
Certificate of Incorporation or Bylaws in connection with or arising out of any
action, suit or proceeding with respect to the administration of the Plan or the
granting of Options under it in which he or she may be involved by reason of
being or having been a member of the Board or Committee at the time of the
action, suit or proceeding.

4. EFFECTIVENESS AND TERMINATION OF THE PLAN.

     The Plan shall become effective as of May 18, 2000, provided that the Plan
is approved by the stockholders of the Company within one year of its adoption.
Any Option outstanding at the time of termination of the Plan shall remain in
effect in accordance with its terms and conditions and those of the Plan. The
Plan shall terminate on the earliest of:

          (a) May 18, 2010; or

          (b) the date when all shares of Stock reserved for issuance under
     Section 5 of the Plan shall have been acquired through exercise of Options
     granted under the Plan; or

          (c) such earlier date as the Board may determine.

5. THE STOCK.

     The aggregate number of shares of Stock issuable under the Plan shall be
two million five hundred thousand shares (2,500,000) or the number and kinds of
shares of capital stock or other securities substituted for the Stock as
provided in Section 8. The aggregate number of shares of Stock issuable under
the Plan may be set aside out of the authorized but unissued shares of Stock not
reserved for any other purpose, or out of shares of Stock held in or acquired
for the treasury of the Company. All shares of Stock subject to an Option that
terminates unexercised for any reason may thereafter be subjected to a new
Option under the Plan.

6. OPTION AGREEMENT.

     Each Grantee shall enter into an Option Agreement with the Company setting
forth the terms and conditions of the Option issued to the Grantee, consistent
with the Plan. The form of Option Agreement may be established at any time or
from time to time by the Committee. No Grantee shall have rights in any Option
unless and until an Option Agreement is entered into with the Company.

7. TERMS AND CONDITIONS OF OPTIONS.

     Options may be granted by the Committee at any time and from time to time
prior to the termination of the Plan. Except as hereinafter provided, Options
granted under the Plan shall be subject to the following terms and conditions:

          (a) GRANTEES.  The Grantees shall be those employees of the Company or
     its Subsidiaries (including officers and directors), and those consultants
     to the Company or its Subsidiaries, selected by the Committee. No Incentive
     Stock Options shall be granted to (i) any person owning Stock or other
     capital stock in the Company possessing more than 10% of the total combined
     voting power of all classes of capital stock of the Company, unless such
     Incentive Stock Option meets the requirements of 7(b) and 7(e); or (ii) any
     director who is not an officer. The maximum number of shares of Stock which
     may be issued pursuant to Options granted to a Grantee within a calendar
     year is 1,000,000.

          (b) PRICE.  The exercise price of an Option shall be no less than the
     Fair Market Value of the Stock, without regard to any restriction, at the
     time the Option is granted. If a Grantee owns more than

                                       3
<PAGE>   4

     10% of the total combined voting power of all classes of stock of the
     Company or any Subsidiary, the exercise price of any Incentive Stock Option
     granted to such individual shall be 110% of the Fair Market Value of the
     Stock.

          (c) PAYMENT FOR STOCK.  The exercise price of an Option shall be paid
     in full at the time of the exercise (i) in cash, or (ii) by certified check
     payable to the Company, or (iii) by other mode of payment (e.g., stock) as
     the Committee may approve.

          (d) LIMITATION.  Notwithstanding any provision of the Plan to the
     contrary, an Option shall not be treated as an Incentive Stock Option to
     the extent the aggregate fair market value (determined as of the time the
     Incentive Stock Option is granted) of Stock for which Incentive Stock
     Options are exercisable for the first time by a Grantee during any calendar
     year exceeds $100,000.

          (e) DURATION AND EXERCISE OF OPTIONS.  Options may be exercised for
     terms of up to but not exceeding ten years from the date of grant. Subject
     to the foregoing, Options shall be exercisable at the times and in the
     amounts (up to the full amount thereof) determined by the Committee at the
     time of grant. If an Option granted under the Plan is exercisable in
     installments the Committee shall determine what events, if any, will make
     it subject to acceleration. The term of an Incentive Stock Option granted
     to an employee who owns more than 10% of the combined voting power of all
     classes of stock of the Company shall not exceed 5 years.

          (f) TERMINATION OF SERVICES.  Upon the termination of a Grantee's
     services for the Company or its Subsidiaries for any reason, Options held
     by the Grantee may only be exercised to the extent and during the period,
     if any, set forth in the Option Agreement.

          (g) TRANSFERABILITY OF OPTION.  No Option shall be transferable except
     by will or the laws of descent and distribution. An Option shall be
     exercisable during the Grantee's lifetime only by the Grantee.

          (h) MODIFICATION, EXTENSION AND RENEWAL OF OPTIONS.  Subject to the
     terms and conditions and within the limitations of the Plan, the Committee
     may modify, extend or renew outstanding Options granted under the Plan, or
     accept the surrender of outstanding options (to the extent not theretofore
     exercised) and authorize the granting of new Options in substitution
     thereof. Notwithstanding the foregoing, however, no modification of an
     Option shall, without the consent of the Grantee, alter or impair any
     rights or obligations under any Option theretofore granted under the Plan
     or adversely affect the status of an Incentive Stock Option.

          (i) OTHER TERMS AND CONDITIONS.  Option Agreements may contain any
     other provision not inconsistent with the Plan that the Committee deems
     appropriate.

8. ADJUSTMENT FOR CHANGES IN THE STOCK.

     (a) In the event the shares of Stock, as presently constituted, shall be
changed into or exchanged for a different number or kind of shares or other
securities of the Company (whether by reason of merger, consolidation,
recapitalization, reclassification, split, reverse split, combination of shares
or otherwise), then there shall be substituted for or added to each share of
Stock theretofore or thereafter subject to an Option the number and kind of
shares of capital stock or other securities into, which each outstanding share
of Stock shall be changed, or for which each such share shall be exchanged, or
to which each such share shall be entitled, as the case may be. The price and
other terms of outstanding Options shall also be appropriately amended to
reflect the foregoing events. In the event there shall be any other change in
the number or kind of outstanding shares of the Stock, or of any capital stock
or other securities into which the Stock shall have been changed or for which it
shall have been exchanged, if the Committee shall, in its sole discretion,
determine that the change equitably requires an adjustment in any Option
theretofore granted or which may be granted under the Plan, then adjustments
shall be made in accordance with its determination.

     (b) Fractional shares resulting from any adjustment in Options pursuant to
this Section 8 may be settled in cash or otherwise as the Committee shall
determine. Notice of any adjustment shall be given by the

                                       4
<PAGE>   5

Company to each holder of an Option that shall have been so adjusted, and the
adjustment (whether or not notice is given) shall be effective and binding for
all purposes of the Plan.

     (c) Notwithstanding Section 8(a), the Committee shall have the power, in
the event of the disposition of all or substantially all of the assets of the
Company, or the dissolution of the Company, or the merger or consolidation of
the Company, or the making of a tender offer to purchase all or a substantial
portion of outstanding Stock of the Company, to amend all outstanding Options
(upon such conditions as it shall deem fit) to (i) permit the exercise of
Options prior to the effective date of the transaction and to terminate all
unexercised Options as of that date, or (ii) require the forfeiture of all
Options, provided the Company pays to each Grantee the excess of the Fair Market
Value of the Stock subject to the Option over the exercise price of the Option,
or (iii) make any other provisions that the Committee deems equitable.

9. AMENDMENT OF THE PLAN.

     The Board may amend the Plan and may correct any defect or supply any
omission or reconcile any inconsistency in the Plan or in any Option in the
manner and to the extent deemed desirable to carry out the Plan without action
on the part of the stockholders of the Company; provided, however, that, except
as provided in Section 8 and this Section 9, unless the stockholders of the
Company shall have first approved thereof (i) the total number of shares of
Stock subject to the Plan shall not be increased, (ii) no Option shall be
exercisable more than ten years after the date it is granted, (iii) the
expiration date of the Plan shall not be extended and (iv) no amendment shall
permit the exercise price of any Option to be less than the Fair Market Value of
the Stock at the time of grant, increase the number of shares of Stock to be
received on exercise of an Option, materially increase the benefits accruing to
a Grantee under an Option or modify the eligibility requirements for
participation in the Plan.

10. INTERPRETATION AND CONSTRUCTION.

     The interpretation and construction of any provision of the Plan by the
Committee shall be final, binding and conclusive for all purposes.

11. APPLICATION OF FUNDS.

     The proceeds received by the Company from the sale of Stock pursuant to
this Plan will be used for general corporate purposes.

12. NO OBLIGATION TO EXERCISE OPTION.

     The granting of an Option shall impose no obligation upon the Grantee to
exercise an Option.

13. PLAN NOT A CONTRACT OF EMPLOYMENT.

     Neither the Plan nor any Option Agreement is a contract of employment, and
the terms of employment of any Grantee shall not be affected in any way by the
Plan or related instruments except as specifically provided therein. The
establishment of the Plan shall not be construed as conferring any legal rights
upon any Grantee for a continuance of employment; nor shall it interfere with
the right of the Company (or its Subsidiary, if applicable) to discharge the
Grantee.

14. EXPENSE OF THE PLAN.

     All of the expenses of administering the Plan shall be paid by the Company.

15. COMPLIANCE WITH APPLICABLE LAW.

     Notwithstanding anything herein to the contrary, the Company shall not be
obligated to cause to be issued or delivered any certificates for shares of
Stock issuable upon exercise of an Option unless and until the Company is
advised by its counsel that the issuance and delivery of the certificates is in
compliance with all applicable laws, regulations of government authorities and
requirements of any exchange upon which shares of

                                       5
<PAGE>   6

Stock are traded. The Company shall in no event be obligated to register any
securities pursuant to the Securities Act of 1933 (as now in effect or as
hereafter amended) or to take any other action in order to cause the issuance
and delivery of certificates to comply with any of those laws, regulations or
requirements. The Committee may require, as a condition of the issuance and
delivery of certificates and in order to ensure compliance with those laws,
regulations and requirements, that the Grantee make such covenants, agreements
and representations as the Committee, in its sole discretion, deems necessary or
desirable. Each Option shall be subject to the further requirement that if at
any time the Committee shall determine in its discretion that the listing or
qualification of the shares of Stock subject to the Option, under any securities
exchange requirements or under any applicable law, or the consent or approval of
any regulatory body, is necessary in connection with the granting of the Option
or the issuance of Stock thereunder, the Option may not be exercised in whole or
in part unless the listing, qualification, consent or approval shall have been
effected or obtained free of any conditions not acceptable to the Committee.

16. GOVERNING LAW.

     Except to the extent preempted by federal law, this Plan shall be construed
and enforced in accordance with, and governed by, the laws of the State of
Delaware.

                                       6

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