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                                                                   EXHIBIT 10.51

                                 PROMISSORY NOTE

                                                        Bloomington, Minnesota
$245,000.00                                                     March 30, 2000



         FOR VALUE RECEIVED, KING FAMILY PARTNERS, an Ohio limited partnership
(the "Maker"), hereby unconditionally promises to pay to POPMAIL.COM, INC., a
Minnesota corporation, or its successors and assigns (the "Payee"), at
Bloomington, Minnesota or at such other place or places as may be designated by
Payee from time to time, the sum of Two Hundred Forty-Five Thousand Dollars
($245,000.00) (the "Principal Sum").

         The Principal Sum, plus interest thereon from the date hereof at the
rate of 5.74 percent per annum, shall be due and payable by Maker to Payee on
March 30, 2003 (the "Maturity Date") in any coin or currency of the United
States of America which, at the time of payment, is legal tender for the payment
of public and private debts.

         All payments on account of this Note, when paid, shall be applied first
to the payment of all interest then due on the unpaid balance of this Note and
the balance, if any, shall be applied to reduction of the unpaid balance of the
Principal Sum. This Note may be prepaid in full or in part at any time without
premium.

         Maker agrees to immediately pay to Holder hereof, upon demand, all
losses, costs and expenses (including attorneys' fees) incurred by Holder for
collection and enforcement of this Note in the event of default or otherwise.

         Maker waives presentment, protest and demand, notice of protest, notice
of dishonor and non-payment of this Note, and expressly agrees that this Note,
or any payment hereunder, may be extended from time to time without in any way
affecting the liability of Maker.

         The terms, conditions and provisions of this Note shall be construed
and enforced according to the laws of the State of Minnesota.

         Notwithstanding any of the provisions of this Note, Payee shall look
solely to the Collateral (as defined in that certain Pledge Agreement between
Maker and PopMail.com, inc. dated December 3, 1999, and amended as of even date
herewith) for the satisfaction of the obligations of this Note or any obligation
in any other instrument securing payment hereof and shall not seek a personal
judgment against Maker except to the extent the laws of the State of Minnesota
make a judgment against Maker necessary in order to enforce the terms of such
instruments. In no event shall the Payee seek to enforce or collect a deficiency
judgment with respect to this Note against Maker.


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         IN WITNESS WHEREOF, the duly authorized officer of Maker has caused
this Note to be executed on the date first above written.

                               King Family Partners,
                               an Ohio limited partnership

                               By: SDK Investments, Inc., its General Partner


                               By: s/ Stephen D. King
                                   ------------------------------------------
                                      Stephen D. King
                                      President