<PAGE>   1
Exhibit 10.1
                              SYMPOSIUM CORPORATION
                                 410 PARK AVENUE
                                    SUITE 830
                            NEW YORK, NEW YORK 10022


                                                              June 16, 2000

To the Holders of Symposium
Corporation Series B
Convertible Preferred Stock


                                Letter Agreement


Ladies and Gentlemen:

                  Reference is made to the Certificate of Designation (the
"Certificate") creating the series of preferred stock of Symposium Corporation,
a Delaware corporation (the "Company"), designated as the Series B Convertible
Preferred Stock, par value $.001 per share (the "Series C Shares"), and the Term
Sheet (the "Term Sheet") describing the terms upon which the Series B Shares
were offered and sold to each of you (each, a "Holder" and collectively, the
"Holders"). The Certificate and the Term Sheet are hereinafter collectively
referred to as the "Documents."

                  Pursuant to the terms and conditions set forth in the Term
Sheet, on January 28, 2000, the Company issued and sold to the Holders, for an
aggregate purchase price of $1,535,000, 15,350 Series B Shares and warrants to
purchase 383,750 shares of Common Stock at an exercise price of $1.50 per share
(the "Original Warrants"). In addition, the Company issued warrants to purchase
58,136 shares of Common Stock at an exercise price of $1.50 per share (the
"Commission Warrants") to D2 Co. LLP, as a fee for arranging the financing.

                  This letter sets forth our agreement, as follows:

         1.       Conversion.

                  On or prior to the Redemption Date (as defined below), each
Holder may, at such Holder's option, convert such Holder's Series B Shares in
accordance with the Documents. Upon such conversion, the Company will issue to
each converting Holder, without additional consideration (and in addition to the
number of shares of Common Stock issuable upon such conversion), the number of
additional shares of Common Stock equal to the excess of: (a) the number of
shares of Common Stock issuable upon such conversion assuming an effective
conversion price of $0.50 per share over (b) the number
<PAGE>   2
of shares of Common Stock issuable upon such conversion at the conversion price
then in effect pursuant to the Documents.


         2.       Redemption.

                  (a) On June 29, 2000 (the "Redemption Date"), upon surrender
         by the Holders of the certificates evidencing the Series B Shares
         (except for Series B Shares converted pursuant to Section 1 above), the
         Company will redeem all of the outstanding Series B Shares at a
         redemption price equal to the Stated Value of such shares as set forth
         in the Certificate together with accrued and unpaid dividends thereon
         through the Redemption Date. The aggregate redemption price as of the
         Redemption Date will be $1,561,436.11 (the "Redemption Price"). The
         portion of the Redemption Price payable to each Holder is set forth on
         Schedule A hereto. The Company will pay the Redemption Price by check
         payable to the order of each Holder or, if such Holder has presented
         the Company with written wire instructions prior to the Redemption
         Date, by wire transfer of immediately available funds to the account
         designated in such instructions.

                  (b) If any Holder fails to surrender to the Company the
         certificates evidencing such Holder's Series B Shares on the Redemption
         Date (or to execute and deliver to the Company a lost certificate
         indemnity in form reasonably satisfactory to the Company), the Company
         will deposit the full redemption price payable in respect of such
         Holder's Series B Shares in escrow with its counsel, Kramer Levin
         Naftalis & Frankel LLP and from and after the Redemption Date, the
         Series B Shares owned by such Holder shall cease to be outstanding and
         such Holder shall have no further rights with respect thereto, other
         than to be paid such redemption price upon surrender of such
         certificates or lost certificate indemnity, as the case may be.

                  (c) By executing and delivering this Letter Agreement, each
         Holder irrevocably waives such Holder's right to receive notice of
         redemption as set forth in the Certificate and agrees that the
         redemption of the Series B Shares in accordance with this Letter
         Agreement will constitute satisfaction in full by the Company of its
         obligation to redeem the Series B Shares pursuant to the Documents.

                  3.       Warrants.

                           (a) On the Redemption Date, the exercise price of the
         Original Warrants and the Commission Warrants will be reduced from
         $1.50 per share to $0.75 per share. In order to effect such reduction,
         each Holder will surrender the certificates evidencing such Holder's
         Original Warrants or Commission Warrants, as applicable, to the Company
         in exchange for a new certificate reflecting such reduced price. In
         addition, on the Redemption Date, (a) the Company will issue to the
         Holders of Original Warrants, pro rata in accordance with the
         respective
<PAGE>   3
         numbers of Original Warrants owned by them, additional warrants to
         purchase an aggregate of 122,800 shares of Common Stock at an exercise
         price of $0.75 per share (the "Additional $0.75 Warrants") and
         additional warrants to purchase an aggregate of 200,000 shares of
         Common Stock at an exercise price of $1.50 per share (the "Additional
         $1.50 Warrants and, together with the Additional $0.75 Warrants, the
         "Additional Warrants"); and (b) the Company will issue to D2 Co. LLP
         additional warrants to purchase 17,820 shares of Common Stock at an
         exercise price of $0.75 per share (the "Additional Commission
         Warrants"). The Original Warrants, as amended in accordance with this
         paragraph, the Commission Warrants, the Additional Warrants and the
         Additional Commission Warrants are hereinafter collectively referred to
         as the "Warrants." Other than the exercise prices (which shall be as
         described above), the terms and conditions of the Additional Warrants
         and the Additional Commission Warrants will be identical to those of
         the Original Warrants and the Commission Warrants and the Holders will
         be entitled to the same registration rights with respect to the shares
         of Common Stock issuable upon exercise of the Additional Warrants and
         Additional Commission Warrants as apply to the shares of Common Stock
         issuable upon exercise of the Original Warrants and Commission
         Warrants. The shares of Common Stock issuable upon exercise of all such
         Warrants are hereinafter collectively referred to as the "Warrant
         Shares."

                           (b) The Holders agree that the Company's agreement in
         Section 1 hereof to issue additional shares of Common Stock to the
         Holders upon conversion of Series B Shares, the reduction of the
         exercise price of the Original Warrants and the Commission Warrants and
         the issuance to the Holders of the Additional Warrants and Additional
         Commission Warrants satisfy in full any claims, whether or not
         previously asserted by the Holders, in respect of the amount or terms
         of securities to which they were or may have been entitled in
         connection with their $1,535,000 investment in the Company in January
         2000 or any right to commissions or fees relating to such investment
         (the "Claims"). Each such Holder, on its own behalf and on behalf of
         its respective officers, directors, partners, managers, equity owners,
         agents, affiliates, executors, administrators, successors and assigns,
         hereby waives and releases the Company, its officers, directors,
         employees, agents, affiliates, successors and assigns from, to the
         fullest extent permitted by applicable law, any claims or causes of
         action arising out of or relating to the amount or terms of securities
         issued to such Holder in connection with such investment or any such
         commissions or fees, except for claims arising under this Letter
         Agreement.

                  4.       Representations and Warranties of Holders.

                           Each of the Holders hereby severally represents and
warrants to the Company, on behalf of itself, as follows:

                           (a) Such Holder is (and on the Redemption Date and
each date on which such Holder purchases Warrant Shares upon exercise of all or
any portion of the
<PAGE>   4
Warrants, such Holder will be) an "accredited investor" within the meaning of
Regulation D, as promulgated by the Securities and Exchange Commission pursuant
to the Securities Act of 1933, as amended (the "Act");

                  (b) Such Holder has such knowledge and experience in financial
and business matters that it is capable of evaluating the merits and risks of
the transactions contemplated hereby and of an investment in the Company's
securities;

                  (c) Such Holder has been furnished and has reviewed the
Company's Annual Report on Form 10-K for the year ended December 31, 1999,
Quarterly Report on Form 10-Q for the quarter ended March 31, 2000 and Current
Report on Form 8-K, as filed with the Commission on June 16, 2000 (which Form
8-K describes the terms and conditions upon which the Company issued shares of
Series A Convertible Preferred Stock, Series C Preferred Stock, and warrants, a
portion of the net proceeds of which will be used to fund the redemption of the
Series B Shares contemplated by this Letter Agreement);

                  (d) Such Holder has had the opportunity to confer with the
Company's management and has obtained such additional information regarding the
Company, its business and capital structure as such Holder has requested in
connection with the transaction contemplated by this Letter Agreement;

                  (e) Such Holder acquired the Original Warrants or Commission
Warrants, is acquiring the Additional Warrants or the Additional Commission
Warrants, as applicable, and will acquire Warrant Shares upon exercise of any
such Warrants, for investment and without a view to the sale, assignment,
transfer or other distribution thereof;

                  (f) Such understands that the Warrants and the Warrant Shares
may not be offered for sale, sold or otherwise transferred except pursuant to an
effective registration statement under the Act and in compliance with the
applicable securities laws of any state or other jurisdiction, or pursuant to an
opinion of counsel satisfactory to the company that such registration is not
required and such compliance has been obtained. The Company may affix an
appropriate legend to any certificate(s) evidencing Warrants or Warrant Shares
to reflect the foregoing.

         6.       Miscellaneous.

                  This Letter Agreement will be governed by the laws of the
State of New York applicable to contracts made and to be performed entirely
within such State. Any claims or disputes relating in any way to this Letter
Agreement shall be submitted to the New York State courts or the United States
District Court for the Southern District of New York and such courts shall have
exclusive jurisdiction over such claims or disputes. The parties hereby consent
to such venue and the personal jurisdiction of such courts and agree not to
contest such venue or assert any claims to move the claim or dispute to another
venue or forum. This Letter Agreement may be executed in counterparts and by
the parties hereto in separate counterparts, each of which shall constitute an
original and all of which together shall constitute one and the same agreement.
This Letter Agreement supersedes any prior understanding or agreement, written
or oral, among the parties hereto relating to the subject matter hereof.
<PAGE>   5
         If the foregoing correctly sets forth our understanding, please so
indicate by signing an enclosed counterpart of this Letter Agreement and
returning it to the undersigned. Upon execution and delivery to the undersigned
of a counterpart of this Letter Agreement by each of the Holders, this Letter
Agreement will constitute a binding agreement among us.

                           Very truly yours,

                           SYMPOSIUM CORPORATION


                           By:________________________
                              Ronald Altbach
                              Chairman and Chief Executive Officer
<PAGE>   6
    Signature Page of Letter Agreement, dated June 16, 2000, among Symposium
    Corporation and the Holders of its Series B Convertible Preferred Shares

Accepted and agreed to as of the
date first above written:


___________________________                 Redeem   / /     Convert   / /
Dominic Chang


___________________________                 Redeem   / /     Convert   / /
Krishnan Thampi


___________________________                 Redeem   / /     Convert   / /
Dublin Holdings LLC
   By:
   Title:

___________________________                 Redeem   / /     Convert   / /
JR Squared LLC
   By:
   Title:


___________________________                 Redeem   / /     Convert   / /
Kerry Fleming


___________________________                 Redeem   / /     Convert   / /
Dominic Bassani

___________________________                 Redeem   / /     Convert   / /
David Ian Mitchell


___________________________                 Redeem   / /     Convert   / /
TCMP3 Capital LLC
   By:
   Title:


___________________________                 Redeem   / /     Convert   / /
Jodi Kirsch
<PAGE>   7
    Signature Page of Letter Agreement, dated June 16, 2000, among Symposium
    Corporation and the Holders of its Series B Convertible Preferred Shares


___________________________                 Redeem   / /     Convert   / /
Stephen J. Posner


___________________________                 Redeem   / /     Convert   / /
Jean Fresa
<PAGE>   8
<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------
                   SCHEDULE A
------------------------------------------------------------------------------------------
                                             CURRENT
------------------------------------------------------------------------------------------
             NAME                           OUTSTANDING        DIVIDEND          TOTAL
------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------
<S>          <C>                           <C>               <C>             <C>
B-1          Dominic Chang                 $ 150,000.00      $ 2,583.33      $ 152,583.33
------------------------------------------------------------------------------------------
B-2          Krishnan Thampi                  50,000.00          861.11         50,861.11
------------------------------------------------------------------------------------------
B-3          Dublin Holdings, Ltd            100,000.00        1,722.22        101,722.22
------------------------------------------------------------------------------------------
B-4          JR Squared LLC                  150,000.00        2,583.33        152,583.33
------------------------------------------------------------------------------------------
B-5          Kerry Fleming                   450,000.00        7,750.00        457,750.00
------------------------------------------------------------------------------------------
B-6          Dominic Bassani                 150,000.00        2,583.33        152,583.33
------------------------------------------------------------------------------------------
B-7          David Jan Mitchell              150,000.00        2,583.33        152,583.33
------------------------------------------------------------------------------------------
B-8          TCMP3 Capital LLC                60,000.00        1,033.33         61,033.33
------------------------------------------------------------------------------------------
B-9          Jodi Kirsch                     200,000.00        3,444.44        203,444.44
------------------------------------------------------------------------------------------
B-10         Stephen Posner                   25,000.00          430.56         25,430.56
------------------------------------------------------------------------------------------
B-11         Jean Fresa                       50,000.00          861.11         50,861.11
------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------
                                           $  1,535,000      $26,436.11    $ 1,561,436.11
------------------------------------------------------------------------------------------
</TABLE>