<PAGE>

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
OR UNDER THE SECURITIES LAWS OF ANY STATE. THIS NOTE MAY NOT BE SOLD,
TRANSFERRED, PLEDGED OR HYPOTHECATED WITHOUT THE PRIOR WRITTEN CONSENT OF THE
COMPANY.

                          MINDSPRING ENTERPRISES, INC.

                                 Promissory Note

$3,078,324.00                                                October 22, 1996

      FOR VALUE RECEIVED, the undersigned, MINDSPRING ENTERPRISES, INC., a
Delaware corporation (herein called the "Company"), hereby promises to pay to
PSINET, INC., a New York corporation, or registered assigns (hereinafter called
the "Payee"), the principal sum of Three Million Seventy Eight Thousand Three
Hundred Twenty Four Dollars ($3,078,324.00) (the "Principal", which shall be
subject to increase or decrease as set forth below). All payments hereunder
shall be made in lawful money of the United States of America, and shall be
subject to the offset and deduction provisions described herein.

Payment

      The Principal shall be payable in monthly installments on the last day of
each calendar month (or, if such day is not a business day, on the next
succeeding business day) as follows: (i) beginning on January 31, 1997, through
and including June 30, 1997, principal in the amount of Fifty Thousand Dollars
($50,000) shall be payable; (ii) beginning on July 31, 1997, through and
including December 31, 1997, principal in the amount of One Hundred Thousand
Dollars ($100,000) shall be payable; (iii) beginning on January 31, 1998,
through and including June 30, 1998, principal in the amount of One Hundred
Fifty Thousand Dollars ($150,000) shall be payable; (iv) beginning on July 31,
1998, through and including November 30, 1998, principal in the amount of Two
Hundred Twenty Five Thousand Dollars ($225,000) shall be payable; and (v) on
December 31, 1998, a final principal payment in the amount of One Hundred Fifty
Three Thousand Three Hundred Twenty Four Dollars ($153,324) shall be payable.
<PAGE>

Late Charges

      If the entire amount of any principal payment is not paid in full within
five (5) days after the date when due, the Company shall pay to the Payee a late
fee equal to two percent (2%) of the amount not paid.

Sale of Note

      This Note has not been registered under the Securities Act of 1933, as
amended (the "1933 Act") or under the securities laws of any state. This Note
may not be sold, transferred, pledged or hypothecated without the prior written
consent of the Company.

      This Note shall be registered on books of the Company that shall be kept
at its principal office for that purpose, and shall be transferable only on such
books by the registered owner hereof in person or by duly authorized attorney
upon surrender of this Note properly endorsed, and only in compliance with the
next preceding paragraph hereof.

Redemption

      The Company may redeem this Note in whole or in part at any time.

Default

      In case of the failure to pay, when due, the principal or any other sum
payable hereunder, and continuance of such failure for five (5) business days
after the date on which such principal or other sum is due (whether upon
maturity hereof, upon any installment payment date, upon any prepayment date,
upon acceleration, or otherwise), the Payee may declare this Note to be due and
payable in full.

Miscellaneous

      Upon receipt by the Company of evidence satisfactory to it of the loss,
theft, destruction or mutilation of this Note, and (in case of loss, theft or
destruction) of indemnity reasonably satisfactory to it, and upon reimbursement
to the Company of all reasonable expenses incidental thereto, and upon surrender
and cancellation of this Note, if mutilated, the Company will make and deliver a
new Note of like tenor in the principal amount of this Note then outstanding in
lieu of such Note. Any Note so made and delivered shall be dated as of the date
to which principal has been paid on the Note lost, stolen, destroyed or
mutilated.


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<PAGE>

      The Company shall have the right to offset and/or deduct, from time to
time and at any time, any amounts of principal payable under this Note against
Losses (as defined in the Asset Purchase Agreement by and between the Company
and Payee, dated as of June 28, 1996 ("Purchase Agreement", which term shall
include all amendments thereto)) asserted against, resulting to, imposed upon or
incurred by the Company for which the Company has a right or claim for
indemnification pursuant to Article 10 of the Purchase Agreement.

      The Company hereby waives presentment, demand, notice, protest and other
demands and notices in connection with the delivery, acceptance or enforcement
of this Note.

      No delay or omission on the part of the Payee in exercising any right
hereunder shall operate as a waiver of such right or of any other right under
this Note, and a waiver, delay or omission on any one occasion shall not be
construed as a bar to or waiver of any such right on any future occasion.

      The Company hereby agrees to pay on demand all costs and expenses,
including, without limitation, reasonable attorneys' fees and legal expenses,
incurred or paid by Payee in enforcing this Note.

      The terms of this Note shall be governed by and construed in accordance
with the laws of the State of New York (but not including the choice of law
rules thereof).

      This Note shall not be valid or obligatory for any purpose until
authenticated by the execution hereof by the Chairman, President or a Vice
President of the Company and registered upon the books of the Company as
hereinabove provided.


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<PAGE>

      IN WITNESS WHEREOF, MINDSPRING ENTERPRISES, INC., a Delaware corporation,
has caused this Note to be signed in its corporate name by its Chairman,
President or a Vice President, by authority duly given, all as of the day and
year first above written.

                                    MINDSPRING ENTERPRISES, INC.

                                    By: /s/ Charles M. Brewer
                                        --------------------------
                                    Title: Chairman & CEO


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