<PAGE>

                                                                   EXHIBIT 10.30

                                PROMISSORY NOTE

$2,000,000.00                                                  Fort Worth, Texas
                                                                  April 26, 2000

     FOR VALUE RECEIVED, on or before October 26, 2000 (the "Maturity Date"),
FlashNet Communications, Inc., a Texas corporation (the "Borrower"), hereby
promises to pay to the order of Prodigy Communications Corporation, a Delaware
corporation (the "Lender"), the lesser of the principal sum of Two Million
Dollars ($2,000,000) or the aggregate unpaid principal amount of all Advances
(defined below) made by the Lender to the Borrower, in immediately available
funds at its principal offices located at 44 South Broadway, White Plains, New
York 10601 (or such other place as Lender may designate), together with interest
on the unpaid principal amount hereof at the rates and on the dates set forth
herein.  The Lender hereby agrees, so long as no Event of Default exists, to
make all Advances as may be requested by the Borrower hereunder prior to the
Maturity Date, provided that the aggregate sum of the principal amount of all
Advances outstanding hereunder from time to time does not exceed $2,000,000.

     The outstanding principal of each Advance hereunder shall accrue interest
at a per annum rate equal to twelve percent.

     Each request for an Advance shall be in writing and shall be made by the
Borrower at least three (3) Business Days prior the requested date of such
Advance.  Each Advance shall be in the minimum amount of $250,000 (and in
integral multiples of $100,000 if in excess thereof).  Each request for an
advance hereunder shall specify the date of such Advance, and the amount of such
Advance. The Lender shall, and is hereby authorized to, record on the schedule
attached hereto, or to otherwise record in accordance with its usual practice,
the date and amount of each Advance and the date and amount of each principal
payment hereunder.

     The Borrower may prepay any Advance without premium or penalty subject to
the Borrower giving at least one (1) Business Day prior written notice to the
Lender.  Any Advances that are repaid may not be reborrowed.

     For the purpose of this Note, the following terms shall have the following
meanings:

     "ADVANCE" shall mean a borrowing under this Note.

     "BUSINESS DAY" shall mean any day other than a Saturday, Sunday, or other
     day on which commercial banks in the State of New York are authorized or
     required to close under the laws of the State of New York.

     "TERMINATION DATE" means the earlier of (1) the Maturity Date and (2) the
     date on which the Lender declares an Event of Default pursuant to the terms
     hereof.

     Interest shall be payable hereunder on each Advance on the Maturity Date.
Interest shall be computed on the basis of a three hundred sixty-five (365) day
year and actual days elapsed.  Upon default or after maturity or after judgment
has been rendered on this Note, each Advance shall bear interest at a rate per
annum equal to fourteen percent (14.0%) per annum.  In addition to, and not in
limitation of, the foregoing, during the continuance of a default hereunder, to
the extent permitted by law, overdue interest, fees (including reasonable
attorney's fees and the
<PAGE>

commitment fee) and other charges payable hereunder shall bear interest from and
including the due date hereof until paid at a rate per annum equal to fourteen
percent (14.0%) per annum. Such rate shall be in effect until all the
obligations of the Borrower to the Lender are paid in full. In no event shall
any interest be at a rate in excess of the maximum rate permitted by law.

     At the option of the holder, this Note shall become immediately due and
payable upon the occurrence and during the continuance at any time of any of the
following events of default (each an "Event of Default"):  (1) default in the
payment or performance of this or any other liability or obligation of the
maker, including the payment of any installment hereunder, or of any endorser or
guarantor of any obligation or liability of the maker, to the holder; (2) the
liquidation, termination, dissolution or the appointment of a receiver for the
maker or its property as a whole; (3) the institution by the maker of any
proceedings under the United States Bankruptcy Code or any other federal or
state law in which the maker is alleged to be insolvent or unable to pay his
debts as they mature or the making by the undersigned of an assignment or trust
mortgage for the benefit of creditors; or (4)(a) the institution against the
maker of any proceedings under the United States Bankruptcy Code or of any other
federal or state law in which the maker is alleged to be insolvent or unable to
pay his debts as they mature, and (b) the failure of the maker to cause such
proceedings to be dismissed or stayed within 30 days; whereupon the holder shall
have then, or at any time thereafter, all of the rights and remedies afforded by
the Uniform Commercial Code as from time to time in effect in the State of New
York or afforded by other applicable law.

     Any expenses incurred in connection with the enforcement or collection of
the Advances or the Lender's rights hereunder, including reasonable attorney's
fees, shall be paid by the Borrower.

     This Note and the rights as described herein are not assignable in whole or
in part by the Borrower, and are personal to the Borrower and may not be relied
upon by any other party.

     No delay or omission on the part of the holder in exercising any right
hereunder shall operate as a waiver of such right or of any other right of such
holder, nor shall any delay, omission or waiver on any one occasion be deemed a
bar to or waiver of the same or any other right on any future occasion.  The
maker and every indorser or guarantor of this Note regardless of the time, order
or place of signing waives presentment, demand, protest and notices of every
kind and assents to any extension or postponement of the time of payment or any
other indulgence, to any substitution, exchange or release of collateral, and to
the addition or release of any other party or person primarily or secondarily
liable.

     None of the terms or provisions of this Note may be excluded, modified, or
amended except by a written instrument duly executed on behalf of the holder
expressly referring hereto and setting forth the provision so excluded, modified
or amended.

     ALL RIGHTS AND OBLIGATIONS HEREUNDER SHALL BE GOVERNED BY THE LAWS OF THE
STATE OF NEW YORK AND THIS NOTE SHALL BE DEEMED TO BE UNDER SEAL.

                                       2
<PAGE>

     EXECUTED as of this 25th day of April, 2000 as an instrument under seal.

                                          FLASHNET COMMUNICATIONS, INC.


                                          By: /s/Andy Jent
                                             -------------------------------
                                          Name: Andy Jent
                                          Title:  Executive Vice President and
                                                  Chief Financial Officer

AGREED:

PRODIGY COMMUNICATIONS CORPORATION

By:     /s/ Andrea S. Hirsch
    -------------------------------------
Name: Andrea S. Hirsch
Title: Executive Vice President, General Counsel

                                       3
<PAGE>

                   SCHEDULE OF LOAN AND PAYMENTS OF PRINCIPAL
                                       TO
                               PROMISSORY NOTE OF
                         FLASHNET COMMUNICATIONS, INC.
                             DATED:  April 26, 2000


<TABLE>
<CAPTION>

                          Principal            Principal
Date                      Amount of             Amount               Unpaid
                           Advance               Paid               Balance
<S>                  <C>                  <C>                  <C>


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</TABLE>

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