<PAGE>

                                                                 EXHIBIT 10.22

              CONFIDENTIAL MATERIALS OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.

                                PROMISSORY NOTE
                                ---------------

                                                        March 7, 1997
$10,000,000                                  Cambridge, Massachusetts

          FOR VALUE RECEIVED, Open Market, Inc. (the "Maker"), promises to pay
to Reed Elsevier Inc. (the "Stockholder"), or order, at the offices of the
Stockholder or at such other place as the holder of this Note may designate, the
principal sum of $10,000,000, together with interest on the unpaid principal
balance of this Note from time to time outstanding at the rate of 8.0% per year
until paid in full.  Principal and interest shall be paid as follows:


     The principal amount of this Note shall be payable in two equal
     installments; the first installment of $5,000,000 (the "First Installment")
     shall be due and payable (in the form of payment determined in accordance
     with the following paragraph) on the first anniversary of the date of this
     Note and the second installment of $5,000,000 (the "Second Installment")
     shall be due and payable in cash on the second anniversary of the date of
     this Note.  All accrued and unpaid interest on the First Installment shall
     be due and payable in cash on the first anniversary hereof.  All accrued
     and unpaid interest on the Second Installment shall be due and payable in
     cash on the second anniversary hereof or, if earlier, on the date of
     payment of the Second Installment.

     The form of payment of the First Installment shall be in cash and/or shares
     of common stock, $.001 par value per share, of the Maker ("Maker Stock")
     based on the Net Revenue (as defined below) of Folio Corporation for the
     one year period ending on December 31, 1997 such that:

     (a)  if the Net Revenue is equal to or greater than ***********, the First
          Installment shall be paid in cash;

     (b)  if the Net Revenue is greater than *********** and less than
          ***********, the First Installment shall be paid in cash equal to the
          sum of ********** plus the amount by which the Net Revenue is greater
          than


<PAGE>

              CONFIDENTIAL MATERIALS OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION.
                        ASTERISKS DENOTE SUCH OMISSIONS.


          *********** and by delivery of Maker Stock with a value equal to
          $5,000,000 less the cash portion of the First Installment;

     (c)  if the Net Revenue is less than ***********, the First Installment
          shall be paid by delivery of Maker Stock with a value of $5,000,000;
          or

     (d)  if the Net Revenue is equal to or greater than ***********, the Second
          Installment shall be paid on the first anniversary hereof.

     Maker and the Stockholder stipulate that the Net Revenue tests set forth in
paragraphs (a), (b), (c) and (d) above (the "Revenue Thresholds") are based on
the mutual expectation that the business of Folio Corporation during 1997 will
be conducted in accordance with the assumptions set forth in Appendix I attached
                                                             ----------
hereto (the "Revenue Assumptions").  If Maker elects to vary the nature of the
business or operations of Folio Corporation from the Revenue Assumptions (other
than in response to changes in general business conditions or other events
beyond the reasonable control of Folio Corporation not contemplated by the
Revenue Assumptions) in a manner that is materially inconsistent with the
Revenue Assumptions and has a material adverse effect on the Net Revenue, then
the Revenue Thresholds shall be equitably adjusted in order to give effect to
the parties' original intentions in light of such changed circumstances.  If
Maker and Stockholder are unable to agree on such equitable adjustment within 60
days after either party requests that one be made, then Maker and the
Stockholder shall appoint an independent certified public accountant (or if the
parties fail to agree on such appointment, the arbitrator provided for in
Section 11.03 of that certain Stock Purchase Agreement dated February 20, 1997
among Maker, Stockholder and Folio Corporation (the "Purchase Agreement") shall
appoint an independent certified public accountant), the compensation of which
shall be paid one-half by Maker and one-half by the Stockholder, which shall
determine whether an equitable adjustment is appropriate and, if so, the nature
of

                                      -2-
<PAGE>

such equitable adjustment, and whose determination shall be conclusive and
binding on the parties absent fraud or manifest error.

     For purposes of verifying Net Revenue as determined utilizing the
assumptions set forth in Appendix I, the Maker's auditors shall deliver to the
                         ----------
Stockholder a statement of Net Revenue for the one year period ending December
31, 1997.  The Stockholder and one firm of certified public accountants acting
on behalf of the Stockholder shall have the right to review the work papers of
the Maker's auditors utilized in preparing the statement and shall have full
access to the books, records, properties and personnel of Folio Corporation for
purposes of verifying the accuracy and fairness of the statement.

     For purposes hereof (i) the value of each share of Maker Stock, if any, to
be delivered on the first anniversary of the date hereof shall be equal to the
average of the reported closing price of a share of Maker Stock on the Nasdaq
National Market for each of the twenty (20) trading days ending on the fourth
trading day immediately preceding the first anniversary of the date hereof and
(ii) "Net Revenue" shall mean the net revenue of Folio Corporation as determined
in accordance with United States generally accepted accounting principles
("USGAAP") and in a manner consistent with the Financial Statements of Folio
Corporation referred to in Section 3.06 of the Purchase Agreement, except to the
extent inconsistent with USGAAP.

     Interest on this Note shall be computed on the basis of a year of 365 days
for the actual number of days elapsed.

     This Note shall become immediately due and payable in cash without notice
or demand upon the occurrence at any time of any of the following events of
default (individually, "an Event of Default" and collectively, "Events of
Default"):

     (1)  default in the payment or performance of any obligation of the Maker
          under this Note;

     (2)  the liquidation, termination of existence, dissolution or business
          failure of the Maker, or the appointment of a receiver or custodian
          for the Maker or any part of its property if such

                                      -3-
<PAGE>

          appointment is not terminated or dismissed within sixty (60) days;

     (3)  the institution against the Maker or any indorser or guarantor of this
          Note of any proceedings under the United States Bankruptcy Code or any
          other federal or state bankruptcy, reorganization, receivership,
          insolvency or other similar law affecting the rights of creditors
          generally, which proceeding is not dismissed within sixty (60) days of
          filing;

     (4)  the institution by the Maker or any indorser or guarantor of this Note
          of any proceedings under the United States Bankruptcy Code or any
          other federal or state bankruptcy, reorganization, receivership,
          insolvency or other similar law affecting the rights of creditors
          generally or the making by the Maker or any indorser or guarantor of
          this Note of a composition or an assignment or trust mortgage for the
          benefit of creditors; or

     (5)  at such time that the aggregate book value of the cash, cash
          equivalents and short-term negotiable investment grade instruments of
          the Maker is less than the sum of the then outstanding principal
          amount of this Note plus $2,000,000.

     Upon the occurrence of an Event of Default, 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 Commonwealth of
Massachusetts or afforded by other applicable law.

     Every amount overdue under this Note shall bear interest from and after the
date on which such amount first became overdue at an annual rate of 10%.  Such
interest on overdue amounts under this Note shall be payable on demand and shall
accrue and be compounded monthly until the obligation of the Maker with respect
to the payment of such interest has been discharged (whether before or after
judgment).

     In no event shall any interest charged, collected or reserved under this
Note exceed the maximum rate then permitted by applicable law and if any such
payment is paid

                                      -4-
<PAGE>

by the Maker, then such excess sum shall be credited by the holder as a payment
of principal.

     Whenever any amount is paid under this Note, all or part of the amount paid
may be applied to principal, premium or interest in such order and manner as
shall be determined by the holder in its discretion.

     The Maker agrees to pay on demand all costs of collection, including
reasonable attorneys' fees, incurred by the holder in enforcing the obligations
of the Maker under this Note.

     No delay or omission on the part of the holder in exercising any right
under this Note 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.

     This Note may be prepaid in whole or in part at any time or from time to
time.  Any such prepayment shall be in cash.  Any such prepayment shall be
without premium or penalty.  Notwithstanding anything to the contrary herein,
any amounts payable hereunder in shares of Maker Stock, may, at the option of
the Maker, be paid in cash.

     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 to this Note and setting forth the provision so excluded,
modified or amended.

     All rights and obligations hereunder shall be governed by the laws of the
Commonwealth of Massachusetts and this Note is executed as an instrument under
seal.

                                      -5-
<PAGE>

ATTEST:                                     OPEN MARKET, INC.


By: /s/ Rick Olin                     By: /s/ Regina O. Sommer
   _______________________               _______________________

Title: Staff Counsel                  Title: CFO
      ____________________                  ____________________

                                      -6-
<PAGE>

                                   APPENDIX I
                                   ----------



The Revenue Assumptions:

          1.  Folio Corporation will be operated as a separate accounting unit
selling and licensing the products and services currently sold or licensed by it
or which it is developing, with segregated accounting records as to revenue and
income statements.

          2.  Folio Corporation will recognize revenue in accordance with
USGAAP, including guidance provided in the Exposure Draft of the Proposed
Statement of Position for Software Revenue Recognition dated June 14, 1996
prepared by the Software Revenue Recognition Working Group, Accounting Standards
Division of the American Institute of Certified Public Accountants.

          3.  Pricing of the products and services of Folio Corporation will be
on a basis substantially consistent with the revenue projections contained in
the Confidential Information Memorandum of Folio Corporation dated January 1997.

          4.  If the products and services of Folio Corporation are bundled for
sales or marketing purposes with products or services of the Maker or one of its
affiliates, then the revenue attributed to Folio Corporation will be prorated
proportionately based on the aggregate list prices of such bundled products
sold, such that all such bundled products will be discounted equally.

                                      -7-