<PAGE>   1
          As filed with the Securities and Exchange Commission on April 13, 2000
                                            Registration No. 333-_______________


                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                  --------------------------------------------

                             REGISTRATION STATEMENT
                                   ON FORM S-8

                                      UNDER
                           THE SECURITIES ACT OF 1933

                 ----------------------------------------------

                              DIGITAL IMPACT, INC.
             (Exact name of Registrant as specified in its charter)

<TABLE>
<S>                         <C>                                                           <C>
                                              177 Bovet Road, Suite 200
         Delaware                            San Mateo, California 94402                             94-3286913
 (State of Incorporation)   (Address of principal executive offices, including zip code)  (IRS Employer Identification Number)
</TABLE>
                 ----------------------------------------------

                                 1998 STOCK PLAN
                            1999 DIRECTOR OPTION PLAN
                        1999 EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the plans)

                 ----------------------------------------------


                                  William Park
                      Chief Executive Officer and Chairman
                            of the Board of Directors
                              DIGITAL IMPACT, INC.
                            177 Bovet Road, Suite 200
                           San Mateo, California 94402
                                 (650) 356-3400
            (Name, address and telephone number of agent for service)

                                    Copy to:
                                Jeffrey D. Saper
                        WILSON SONSINI GOODRICH & ROSATI
                            Professional Corporation
                               650 Page Mill Road
                            Palo Alto, CA 94304-1050

<TABLE>
<CAPTION>
                                                 CALCULATION OF REGISTRATION FEE
================================================================================================================================
                                                                      PROPOSED MAXIMUM     PROPOSED MAXIMUM
                                                     AMOUNT TO BE    OFFERING PRICE PER   AGGREGATE OFFERING       AMOUNT OF
       TITLE OF SECURITIES TO BE REGISTERED           REGISTERED            SHARE                PRICE         REGISTRATION FEE
--------------------------------------------------- ---------------- -------------------- -------------------- -----------------
<S>                                                     <C>              <C>                  <C>                  <C>
Common Stock, $0.001 par value, to be issued
   under the 1998 Stock Plan                            4,470,545         $5.332(1)          $23,836,946           $6,293

                                                        3,385,993        $15.156(2)          $51,318,110          $13,548

Common Stock, $0.001 par value, to be issued
   under the 1999 Director Option Plan                    500,000        $15.156(2)           $7,578,000           $2,001

Common Stock, $0.001 par value, to be issued
   under the 1999 Employee Stock Purchase Plan            700,000        $15.156(2)          $10,609,200           $2,801

                                            TOTAL:      9,056,538                            $93,342,256          $24,643
================================================================================================================================
</TABLE>

(1)  Estimated in accordance with Rule 457(h) solely for the purpose of
     calculating the registration fee, based on the weighted average exercise
     price of the outstanding options as of April 11, 2000.

(2)  Estimated in accordance with Rule 457(h) solely for the purpose of
     calculating the registration fee based on the price of $15.156 per share,
     which was the average of the high and low price per share of the Common
     Stock as reported on the Nasdaq National Market on April 11, 2000.


<PAGE>   2

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS


Item 1. Plan Information*

Item 2. Registrant Information


---------------
* Information required by Part I to be contained in the Section 10(a) prospectus
  is omitted from this Registration Statement in accordance with Rule 428 under
  the Securities Act of 1933, as amended, and the "Note" to Part I of Form S-8.


                                       2

<PAGE>   3


                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Information Incorporated by Reference.

     There are hereby incorporated by reference in this Registration Statement
the following documents and information heretofore filed with the Securities and
Exchange Commission:

          (a)  The Company's Registration Statement on Form S-1 (File No.
     333-87299) as amended, filed pursuant to the Securities Act of 1933, as
     amended (the "SECURITIES ACT"), relating to the Company's initial public
     offering of its Common Stock.

          (b)  The Company's Registration Statement on Form 8-A filed pursuant
     to Section 12 of the Securities and Exchange Act 1934 (the "EXCHANGE ACT")
     on October 22, 1999, and any further amendment or report filed hereafter
     for the purpose of updating any such description.

          (c)  The Company's Quarterly Report on Form 10-Q for the fiscal
     quarter ended December 31, 1999.

          (d)  All documents subsequently filed by the Company pursuant to
     Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the date of
     this Registration Statement and prior to the filing of a post-effective
     amendment which indicates that all securities offered have been sold or
     which deregisters all securities then remaining unsold, shall be deemed to
     be incorporated by reference in this Registration Statement and to be part
     hereof from the date of filing such documents.

Item 4. Description of Securities.

     Not applicable.

Item 5. Interests of Named Experts and Counsel.

     Persons associated with Wilson Sonsini Goodrich & Rosati are the holders of
options to acquire an aggregate of 20,000 shares of the Company's Common Stock.

Item 6. Indemnification of Directors and Officers.

     Section 145 of the Delaware General Corporation Law permits a corporation
to include in its charter documents, and in agreements between the corporation
and its directors and officers, provisions expanding the scope of
indemnification beyond that specifically provided by the current law.

     Article VIII of the Company's Restated Certificate of Incorporation
provides for the indemnification of directors to the fullest extent permissible
under Delaware law.

     Article VI of the Company's Bylaws provides for the indemnification of
officers, directors and third parties acting on behalf of the Company if such
person acted in good faith and in a manner reasonably believed to be in and not
opposed to the best interest of the Company, and, with respect to any criminal
action or proceeding, the indemnified party had no reason to believe his or her
conduct was unlawful.

                                       3

<PAGE>   4

Item 7. Exemption from Registration Claimed.

     Not applicable.

Item 8. Exhibits.

<TABLE>
<CAPTION>
     Exhibit
     Number
     -------
      <S>          <C>
       4.1*        1998 Stock Plan, as amended
       4.2*        1999 Director Option Plan
       4.3*        1999 Employee Stock Purchase Plan
       5.1         Opinion of Wilson Sonsini Goodrich & Rosati, P.C.
      23.1         Consent of Independent Auditors
      23.2         Consent of Counsel (contained in Exhibit 5.1)
      25.1         Power of Attorney (See signature page)
</TABLE>

---------------
*    Incorporated by reference to the Registrant's Registration Statement on
     Form S-1 (File No. 333-87299), as amended, declared effective by the
     Securities and Exchange Commission on November 22, 1999.

Item 9. Undertakings.

     (a)  The Company hereby undertakes:

          (1)  To file, during any period in which offers or sales are being
made, a post-effective amendment to this Registration Statement to include any
material information with respect to the plan of distribution not previously
disclosed in the Registration Statement or any material change to such
information in the Registration Statement.

          (2)  That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
Registration Statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3)  To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

     (b)  The Company hereby undertakes that, for purposes of determining any
liability under the Securities Act, each filing of a report by the Company
pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where
applicable, each filing of an employee benefit plan's annual report pursuant to
Section 15(d) of the Exchange Act) that is incorporated by reference in the
Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.


                                       4

<PAGE>   5

     (c)  Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Company pursuant to the foregoing provisions, or otherwise, the Company
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Company of expenses
incurred or paid by a director, officer or controlling person of the Company in
the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Company will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.



                                       5

<PAGE>   6

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Mateo, State of California, on April 13, 2000.

                                 DIGITAL IMPACT, INC.

                                 By: /s/ WILLIAM PARK
                                     ---------------------------
                                     William Park
                                     Chief Executive Officer and Chairman of the
                                     Board of Directors


                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints William Park and David Oppenheimer, jointly and
severally, his attorneys-in-fact, each with full power of substitution, for him
in any and all capacities, to sign any amendments to this Registration Statement
on Form S-8, and to file the same, with exhibits thereto and other documents in
connection therewith, with the Securities and Exchange Commission, hereby
ratifying and confirming all that each of said attorneys-in-fact, or his
substitute or substitutes, may do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities on April 13, 2000.

<TABLE>
<CAPTION>
            Signature                                                     Title
-------------------------------------         -------------------------------------------------------------------
<S>                                                <C>
/s/ WILLIAM PARK                                   Chief Executive Officer and Chairman of the Board of
------------------------------------               Directors (Principal Executive Officer)
William Park

/s/ DAVID OPPENHEIMER                              Vice President, Finance, Chief Financial Officer, Treasurer
------------------------------------               and Secretary (Principal Financial and Accounting Officer)
David Oppenheimer                                  Chief Technology Officer and Director

/s/ GERARDO CAPIEL                                 Director
------------------------------------
Gerardo Capiel

/s/ RUTHANN QUINDLEN                               Director
------------------------------------
Ruthann Quindlen

/s/ WARREN PACKARD                                 Director
------------------------------------
Warren Packard

/s/ MICHAEL BROWN                                  Director
------------------------------------
Michael Brown
</TABLE>

                                       7

<PAGE>   7


                                INDEX TO EXHIBITS


<TABLE>
<CAPTION>
     Exhibit
     Number        Description
     -------       -----------
      <S>          <C>
       4.1*        1998 Stock Plan, as amended
       4.2*        1999 Director Option Plan
       4.3*        1999 Employee Stock Purchase Plan
       5.1         Opinion of Wilson Sonsini Goodrich & Rosati, P.C.
      23.1         Consent of Independent Auditors
      23.2         Consent of Counsel (contained in Exhibit 5.1)
      25.1         Power of Attorney (See signature page)
</TABLE>
-----------------------
*    Incorporated by reference to the Registrant's Registration Statement on
     Form S-1 (File No. 333-87299), as amended, declared effective by the
     Securities and Exchange Commission on November 22, 1999.


                                       8
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 15128}]
{"company-data": {"conformed-name": "DIGITAL IMPACT INC /DE/", "cik": "0001095105", "assigned-sic": "7389", "irs-number": "943286913", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-34678", "film-number": "600018"}, "business-address": {"street1": "177 BOVER ROAD SUITE 200", "city": "SAN MATEO", "state": "CA", "zip": "94402", "phone": "6503563404"}, "mail-address": {"street1": "177 BOVER ROAD SUITE 200", "city": "SAN MATEO", "state": "CA", "zip": "94402"}}
1
          As filed with the Securities and Exchange Commission on April 13, 2000
                                            Registration No. 333-_______________

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                  --------------------------------------------

                             REGISTRATION STATEMENT
                                   ON FORM S-8

                                      UNDER
                           THE SECURITIES ACT OF 1933

                 ----------------------------------------------

                              DIGITAL IMPACT, INC.
             (Exact name of Registrant as specified in its charter)
177 Bovet Road, Suite 200
         Delaware                            San Mateo, California 94402                             94-3286913
 (State of Incorporation)   (Address of principal executive offices, including zip code)  (IRS Employer Identification Number)
----------------------------------------------

                                 1998 STOCK PLAN
                            1999 DIRECTOR OPTION PLAN
                        1999 EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the plans)

                 ----------------------------------------------

                                  William Park
                      Chief Executive Officer and Chairman
                            of the Board of Directors
                              DIGITAL IMPACT, INC.
                            177 Bovet Road, Suite 200
                           San Mateo, California 94402
                                 (650) 356-3400
            (Name, address and telephone number of agent for service)

                                    Copy to:
                                Jeffrey D. Saper
                        WILSON SONSINI GOODRICH & ROSATI
                            Professional Corporation
                               650 Page Mill Road
                            Palo Alto, CA 94304-1050
CALCULATION OF REGISTRATION FEE
================================================================================================================================
                                                                      PROPOSED MAXIMUM     PROPOSED MAXIMUM
                                                     AMOUNT TO BE    OFFERING PRICE PER   AGGREGATE OFFERING       AMOUNT OF
       TITLE OF SECURITIES TO BE REGISTERED           REGISTERED            SHARE                PRICE         REGISTRATION FEE
--------------------------------------------------- ---------------- -------------------- -------------------- -----------------
Common Stock, $0.001 par value, to be issued
   under the 1998 Stock Plan                            4,470,545         $5.332(1)          $23,836,946           $6,293

                                                        3,385,993        $15.156(2)          $51,318,110          $13,548

Common Stock, $0.001 par value, to be issued
   under the 1999 Director Option Plan                    500,000        $15.156(2)           $7,578,000           $2,001

Common Stock, $0.001 par value, to be issued
   under the 1999 Employee Stock Purchase Plan            700,000        $15.156(2)          $10,609,200           $2,801

                                            TOTAL:      9,056,538                            $93,342,256          $24,643
================================================================================================================================
(1)  Estimated in accordance with Rule 457(h) solely for the purpose of
     calculating the registration fee, based on the weighted average exercise
     price of the outstanding options as of April 11, 2000.

(2)  Estimated in accordance with Rule 457(h) solely for the purpose of
     calculating the registration fee based on the price of $15.156 per share,
     which was the average of the high and low price per share of the Common
     Stock as reported on the Nasdaq National Market on April 11, 2000.
2

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1. Plan Information*

Item 2. Registrant Information

---------------
* Information required by Part I to be contained in the Section 10(a) prospectus
  is omitted from this Registration Statement in accordance with Rule 428 under
  the Securities Act of 1933, as amended, and the "Note" to Part I of Form S-8.

                                       2
3

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Information Incorporated by Reference.

     There are hereby incorporated by reference in this Registration Statement
the following documents and information heretofore filed with the Securities and
Exchange Commission:

          (a)  The Company's Registration Statement on Form S-1 (File No.
     333-87299) as amended, filed pursuant to the Securities Act of 1933, as
     amended (the "SECURITIES ACT"), relating to the Company's initial public
     offering of its Common Stock.

          (b)  The Company's Registration Statement on Form 8-A filed pursuant
     to Section 12 of the Securities and Exchange Act 1934 (the "EXCHANGE ACT")
     on October 22, 1999, and any further amendment or report filed hereafter
     for the purpose of updating any such description.

          (c)  The Company's Quarterly Report on Form 10-Q for the fiscal
     quarter ended December 31, 1999.

          (d)  All documents subsequently filed by the Company pursuant to
     Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the date of
     this Registration Statement and prior to the filing of a post-effective
     amendment which indicates that all securities offered have been sold or
     which deregisters all securities then remaining unsold, shall be deemed to
     be incorporated by reference in this Registration Statement and to be part
     hereof from the date of filing such documents.

Item 4. Description of Securities.

     Not applicable.

Item 5. Interests of Named Experts and Counsel.

     Persons associated with Wilson Sonsini Goodrich & Rosati are the holders of
options to acquire an aggregate of 20,000 shares of the Company's Common Stock.

Item 6. Indemnification of Directors and Officers.

     Section 145 of the Delaware General Corporation Law permits a corporation
to include in its charter documents, and in agreements between the corporation
and its directors and officers, provisions expanding the scope of
indemnification beyond that specifically provided by the current law.

     Article VIII of the Company's Restated Certificate of Incorporation
provides for the indemnification of directors to the fullest extent permissible
under Delaware law.

     Article VI of the Company's Bylaws provides for the indemnification of
officers, directors and third parties acting on behalf of the Company if such
person acted in good faith and in a manner reasonably believed to be in and not
opposed to the best interest of the Company, and, with respect to any criminal
action or proceeding, the indemnified party had no reason to believe his or her
conduct was unlawful.

                                       3
4

Item 7. Exemption from Registration Claimed.

     Not applicable.

Item 8. Exhibits.
Exhibit
     Number
     -------
4.1*        1998 Stock Plan, as amended
       4.2*        1999 Director Option Plan
       4.3*        1999 Employee Stock Purchase Plan
       5.1         Opinion of Wilson Sonsini Goodrich & Rosati, P.C.
      23.1         Consent of Independent Auditors
      23.2         Consent of Counsel (contained in Exhibit 5.1)
      25.1         Power of Attorney (See signature page)
---------------
*    Incorporated by reference to the Registrant's Registration Statement on
     Form S-1 (File No. 333-87299), as amended, declared effective by the
     Securities and Exchange Commission on November 22, 1999.

Item 9. Undertakings.

     (a)  The Company hereby undertakes:

          (1)  To file, during any period in which offers or sales are being
made, a post-effective amendment to this Registration Statement to include any
material information with respect to the plan of distribution not previously
disclosed in the Registration Statement or any material change to such
information in the Registration Statement.

          (2)  That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
Registration Statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3)  To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

     (b)  The Company hereby undertakes that, for purposes of determining any
liability under the Securities Act, each filing of a report by the Company
pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where
applicable, each filing of an employee benefit plan's annual report pursuant to
Section 15(d) of the Exchange Act) that is incorporated by reference in the
Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

                                       4
5

     (c)  Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Company pursuant to the foregoing provisions, or otherwise, the Company
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Company of expenses
incurred or paid by a director, officer or controlling person of the Company in
the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Company will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                       5
6

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Mateo, State of California, on April 13, 2000.

                                 DIGITAL IMPACT, INC.

                                 By: /s/ WILLIAM PARK
                                     ---------------------------
                                     William Park
                                     Chief Executive Officer and Chairman of the
                                     Board of Directors

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints William Park and David Oppenheimer, jointly and
severally, his attorneys-in-fact, each with full power of substitution, for him
in any and all capacities, to sign any amendments to this Registration Statement
on Form S-8, and to file the same, with exhibits thereto and other documents in
connection therewith, with the Securities and Exchange Commission, hereby
ratifying and confirming all that each of said attorneys-in-fact, or his
substitute or substitutes, may do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities on April 13, 2000.
Signature                                                     Title
-------------------------------------         -------------------------------------------------------------------
/s/ WILLIAM PARK                                   Chief Executive Officer and Chairman of the Board of
------------------------------------               Directors (Principal Executive Officer)
William Park

/s/ DAVID OPPENHEIMER                              Vice President, Finance, Chief Financial Officer, Treasurer
------------------------------------               and Secretary (Principal Financial and Accounting Officer)
David Oppenheimer                                  Chief Technology Officer and Director

/s/ GERARDO CAPIEL                                 Director
------------------------------------
Gerardo Capiel

/s/ RUTHANN QUINDLEN                               Director
------------------------------------
Ruthann Quindlen

/s/ WARREN PACKARD                                 Director
------------------------------------
Warren Packard

/s/ MICHAEL BROWN                                  Director
------------------------------------
Michael Brown
7
7

                                INDEX TO EXHIBITS
Exhibit
     Number        Description
     -------       -----------
4.1*        1998 Stock Plan, as amended
       4.2*        1999 Director Option Plan
       4.3*        1999 Employee Stock Purchase Plan
       5.1         Opinion of Wilson Sonsini Goodrich & Rosati, P.C.
      23.1         Consent of Independent Auditors
      23.2         Consent of Counsel (contained in Exhibit 5.1)
      25.1         Power of Attorney (See signature page)
-----------------------
*    Incorporated by reference to the Registrant's Registration Statement on
     Form S-1 (File No. 333-87299), as amended, declared effective by the
     Securities and Exchange Commission on November 22, 1999.

                                       8