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                                                                   Exhibit 10.23

                         Intermedia Communications Inc.
                             3625 Queen Palm Drive
                             Tampa, Florida  33619



                                                  June 2, 1999



Digex, Incorporated
One Digex Plaza
Beltsville, Maryland  20705

Ladies and Gentlemen:

     In connection with the proposed initial public offering ("IPO") of Digex,
                                                               ---
Incorporated ("Digex"), Intermedia Communications Inc. ("Intermedia") and Digex
               -----                                     ----------
wish to confirm their understanding as set forth in this letter.

     Intermedia and Digex acknowledge that Digex will be required to use all of
the net proceeds of the IPO, if one is consummated, to purchase or construct
Telecommunications Related Assets (as defined in the 12-1/2% Senior Discount
Notes Indenture, dated May 14, 1996 (the "Indenture"), between Intermedia and
                                          ---------
SunTrust Bank. Central Florida, National Association, as trustee) within 270
days after the closing of the IPO.  Intermedia and Digex agree that during such
270-day period:

1.   Intermedia, in consultation with the management of Digex, shall, from time
     to time, determine the amount of funds required by Digex to meet its
     working capital needs or to fund its operating losses ("Unrestricted Uses")
                                                             -----------------
     during the next calendar month.  Within five days of determination of the
     amount required by Digex for Unrestricted Uses, Intermedia shall provide to
     Digex a list of Telecommunications Related Assets having a purchase price
     at least equal to such amount to be purchased by Digex (the "Designated
                                                                  ----------
     Assets") and shall designate, and, if necessary, make arrangements with (on
     ------
     Digex's behalf), a vendor or vendors from which Digex should purchase the
     Designated Assets.  Digex shall purchase the Designated Assets from the
     vendor(s) designated by Intermedia from time to time as reasonably required
     to fund Unrestricted Uses, and Intermedia shall purchase from Digex, the
     Designated Assets at Digex's cost thereof promptly following each purchase.

2.   If on the 260th day after the closing of the IPO there remains an amount
     (the "Remaining Amount") of the net proceeds of the IPO that has not been
           ----------------
     used by Digex to purchase or construct Telecommunications Related Assets,
     then


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Digex, Incorporated
Page 2

     Intermedia shall provide to Digex a list of Designated Assets, and, if
     necessary, make arrangements with (on Digex's behalf), a vendor or vendors
     from which Digex should purchase the Designated Assets.  The purchase price
     of such Designated Assets from such designated vendor(s) shall at least
     equal the Remaining Amount.  Within five days after its receipt of such
     notice from Intermedia, Digex shall purchase the Designated Assets from the
     vendor(s) designated by Intermedia.  If and to the extent that the purchase
     price of such Designated Assets exceeds the Remaining Amount, Intermedia
     shall advance such difference to Digex prior to such purchase.  Promptly
     following any such purchase, Digex shall sell to Intermedia, and Intermedia
     shall purchase from Digex, the Designated Assets at Digex's cost thereof.

3.   Intermedia represents and warrants to Digex that Digex's use for
     Unrestricted Uses of a portion of the amounts received by it from
     Intermedia designated by Intermedia as unrestricted funds ("Unrestricted
                                                                 ------------
     Portion") in any purchase and sale transaction pursuant to paragraphs 1 or
     -------
     2 will not violate, or result in a default by Intermedia under, the
     provisions of the Indenture.  The amount of the Unrestricted Portion shall
     be determined based on a reasonable projection of Digex's need for funds
     for Unrestricted Uses during the period commencing on the date of such
     purchase and sale and ending on the first anniversary of the closing of the
     IPO.

4.   Digex represents, warrants and covenants to Intermedia that it shall use
     the net proceeds of the IPO only to purchase or construct
     Telecommunications Related Assets and as provided in this letter agreement.

5.   Each of Digex and Intermedia agrees to cooperate with the other, and to do,
     execute, acknowledge and deliver such further acts, instruments and
     assurances as shall be necessary or desirable to carry out the provisions,
     and the intents and purposes of this letter agreement.  Notwithstanding any
     of the procedures set forth in this letter agreement, with the consent of
     both parties, Intermedia may advance to Digex on a daily basis Digex's cash
     requirements for Unrestricted Uses and purchases of Telecommunications
     Related Assets.  In such circumstances, at the end of every calendar month,
     Intermedia shall prepare and provide to Digex a statement of reconciliation
     of all advances and expenditures made by Intermedia to Digex or on Digex
     behalf during the month-ended, and Digex shall make a corresponding
     transfer of funds to Intermedia.
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Digex, Incorporated
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     Please confirm your understanding and acceptance of the foregoing by
signing in the space provided below.

                              Very truly yours,

                              INTERMEDIA COMMUNICATIONS INC.


                              By:  /s/  RAYMOND L. LAWLESS
                                  ------------------------
                                  Name: Raymond L. Lawless
                                  Title: Vice President of Finance and Treasurer



Agreed and Accepted
This 2nd day of June, 1999

DIGEX, INCORPORATED


By:  /s/ NANCY G. FAIGEN
    --------------------
    Name: Nancy G. Faigen
    Title: Chief Executive Officer