AMENDMENT NO. 1 TO EXECUTIVE RETENTION AGREEMENT

Exhibit 10.6

AMENDMENT NO. 1 TO EXECUTIVE RETENTION AGREEMENT

This Amendment No. 1 to Executive Retention Agreement is made this 26th day of July, 2007, by and between Peter L. Gray (the “Executive”) and CMGI, Inc. (the “Company”).

Whereas, the Executive and the Company are parties to an Executive Retention Agreement dated August 28, 2002 (the “Retention Agreement”); and

Whereas, the Executive and the Company desire to amend the Retention Agreement as set forth herein;

Now, therefore, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties agree as follows:

1. Section 2(a) of the Retention Agreement is hereby amended to add the following:

“In addition, all of the Executive’s stock options and/or restricted stock which are then outstanding shall be immediately vested, such vested awards that were granted as restricted stock shall be free of restrictions and such vested awards that were granted as options shall remain exercisable for a period of 6 months following the Executive’s last day of employment (but not to exceed the original term of such awards).”

2. The Retention Agreement is hereby amended to add the following Sections 2(d) and 2(e):

“(d) Payments to the Executive under Sections 2(a) and 2(b) shall be bifurcated into two portions, consisting of the portion, if any, that includes the maximum amount of the payments that does not constitute “nonqualified deferred compensation” within the meaning of Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”), and the portion, if any, that includes the excess of the total payments that does constitute nonqualified deferred compensation. Payments hereunder shall first be made from the portion that does not consist of nonqualified deferred compensation until such portion is exhausted and then shall be made from the portion that does constitute nonqualified deferred compensation. Notwithstanding the foregoing, if the Executive is a “specified employee” as defined in Section 409A(a)(3)(B)(i) of the Code, the commencement of the delivery of the portion that constitutes nonqualified deferred compensation will be delayed to the date that is 6 months and one day after the Executive’s termination of employment (the “Earliest Payment Date”). Any payments that are delayed pursuant to the preceding sentence shall be paid pro rata during the period beginning on the Earliest Payment Date and ending on the date that is 12 months following termination of the Executive’s employment. The determination of whether, and the extent to which, any of the payments to be made to the Executive hereunder are nonqualified deferred compensation shall be made after the application of all applicable exclusions under Treasury Reg. § 1.409A-1(b)(9). Any payments that are intended to qualify for the exclusion for separation pay due to involuntary separation from service set forth in Treasury Regulation Section 1.409A-1(b)(9)(iii) must be paid no later than the last day of the second taxable year of the Executive following the taxable year of the Executive in which the Executive’s termination of employment occurs.

(e) (i) Notwithstanding any other provision of this Agreement, except as set forth in Section 2(e)(ii), in the event that the Company undergoes a “Change in Ownership or Control” (as defined below), the Company shall not be obligated to provide to the Executive a portion of any “Contingent Compensation Payments” (as defined below) that the Executive would otherwise be entitled to receive to the extent necessary to eliminate any “excess parachute payments” (as defined in Section 280G(b)(1) of the Code) for the Executive. For purposes of this Section 2(e), the Contingent Compensation Payments so eliminated shall be referred to as the “Eliminated Payments” and the aggregate amount (determined in accordance with Treasury Regulation Section 1.280G-1, Q/A-30 or any successor provision) of the Contingent Compensation Payments so eliminated shall be referred to as the “Eliminated Amount.”

(ii) Notwithstanding the provisions of Section 2(e)(i), no such reduction in Contingent Compensation Payments shall be made if (i) the Eliminated Amount (computed without regard to this sentence) exceeds (ii) the aggregate present value (determined in accordance with Treasury Regulation Section 1.280G-1, Q/A-31 and Q/A-32 or any successor provisions) of the amount of any additional taxes that would be incurred by the Executive if the Eliminated Payments (determined without regard to this sentence) were paid to him (including, state and federal income taxes on the Eliminated Payments, the excise tax imposed by Section 4999 of the Code payable with respect to all of the Contingent Compensation Payments in excess of the Executive’s “base amount” (as defined in Section 280G(b)(3) of the Code), and any withholding taxes). The override of such reduction in Contingent Compensation Payments pursuant to this Section 2(e)(ii) shall be referred to as a “Section 2(e)(ii) Override.” For purposes of this paragraph, if any federal or state income taxes would be attributable to the receipt of any Eliminated Payment, the amount of such taxes shall be computed by multiplying the amount of the Eliminated Payment by the maximum combined federal and state income tax rate provided by law.

(iii) For purposes of this Section 2(e), the following terms shall have the following respective meanings:

(A) “Change in Ownership or Control” shall mean a change in the ownership or effective control of the Company or in the ownership of a substantial portion of the assets of the Company determined in accordance with Section 280G(b)(2) of the Code.

(B) “Contingent Compensation Payment” shall mean any payment (or benefit) in the nature of compensation that is made or made available (under this Agreement or otherwise) to a “disqualified individual” (as defined in Section 280G(c) of the Code) and that is contingent (within the meaning of Section 280G(b)(2)(A)(i) of the Code) on a Change in Ownership or Control of the Company.

(iv) Any payments or other benefits otherwise due to the Executive following a Change in Ownership or Control that could reasonably be characterized (as determined by the Company) as Contingent Compensation Payments (the “Potential Payments”) shall not be made until the dates provided for in this Section 2(e)(iv). Within 30 days after each date on which the Executive first becomes entitled to receive (whether or not then due) a Contingent Compensation Payment relating to such Change in Ownership or Control, the Company shall determine and notify the Executive (with reasonable detail regarding the basis for its determinations) (i) which Potential Payments constitute Contingent Compensation Payments, (ii) the Eliminated Amount and (iii) whether the

Section 2(e)(ii) Override is applicable. Within 30 days after delivery of such notice to the Executive, the Executive shall deliver a response to the Company (the “Executive Response”) stating either (A) that he agrees with the Company’s determination pursuant to the preceding sentence, in which case he shall indicate, if applicable, which Contingent Compensation Payments, or portions thereof (the aggregate amount of which, determined in accordance with Treasury Regulation Section 1.280G-1, Q/A-30 or any successor provision, shall be equal to the Eliminated Amount), shall be treated as Eliminated Payments or (B) that he disagrees with such determination, in which case he shall set forth (i) which Potential Payments should be characterized as Contingent Compensation Payments, (ii) the Eliminated Amount, (iii) whether the Section 2(e)(ii) Override is applicable, and (iv) which (if any) Contingent Compensation Payments, or portions thereof (the aggregate amount of which, determined in accordance with Treasury Regulation Section 1.280G-1, Q/A-30 or any successor provision, shall be equal to the Eliminated Amount, if any), shall be treated as Eliminated Payments. In the event that the Executive fails to deliver an Executive Response on or before the required date, the Company’s initial determination shall be final and the Contingent Compensation Payments that shall be treated as Eliminated Payments shall be determined by the Company in its absolute discretion. If the Executive states in the Executive Response that he agrees with the Company’s determination, the Company shall make the Potential Payments to the Executive within three business days following delivery to the Company of the Executive Response (except for any Potential Payments which are not due to be made until after such date, which Potential Payments shall be made on the date on which they are due). If the Executive states in the Executive Response that he disagrees with the Company’s determination, then, for a period of 60 days following delivery of the Executive Response, the Executive and the Company shall use good faith efforts to resolve such dispute. If such dispute is not resolved within such 60-day period, such dispute shall be settled exclusively by arbitration in Boston, Massachusetts, in accordance with the rules of the American Arbitration Association then in effect. Judgment may be entered on the arbitrator’s award in any court having jurisdiction. The Company shall, within three business days following delivery to the Company of the Executive Response, make to the Executive those Potential Payments as to which there is no dispute between the Company and the Executive regarding whether they should be made (except for any such Potential Payments which are not due to be made until after such date, which Potential Payments shall be made on the date on which they are due). The balance of the Potential Payments shall be made within three business days following the resolution of such dispute.

(v) The provisions of this Section 2(e) are intended to apply to any and all payments or benefits available to the Executive under this Agreement or any other agreement or plan of the Company under which the Executive receives Contingent Compensation Payments.”

3. Section 3(c) of the Retention Agreement is hereby amended and restated in its entirety to read as follows:

“(c) “Good Reason” shall mean: (i) the unilateral relocation by the Company of the Executive’s principal work place for the Company to a site more than 60 miles from the Executive’s principal office, (ii) a material reduction in the Executive’s then-current salary without the Executive’s consent or (iii) material diminution of the Executive’s duties, authority or responsibilities, without the Executive’s consent. In order to establish “Good Reason” for a termination, the Executive must provide notice to the Company of

the existence of the condition giving rise to the “Good Reason” within 90 days following the initial existence of the condition, and the Company has 30 days following receipt of such notice to remedy such condition.”

4. Section 3(d) of the Retention Agreement is hereby amended and restated in its entirety to read as follows:

“(d) “Change of Control” shall mean the first to occur of any of the following:

(A) the acquisition by an individual, entity or group (within the meaning of Section 13(d)(3) or 14(d)(2) of the Securities Exchange Act of 1934 (the “Exchange Act”)) (a “Person”) of beneficial ownership of any capital stock of the Company if, after such acquisition, such Person beneficially owns (within the meaning of Rule 13d-3 promulgated under the Exchange Act) 50% or more of either (x) the then-outstanding shares of common stock of the Company (the “Outstanding Company Common Stock”) or (y) the combined voting power of the then-outstanding securities of the Company entitled to vote generally in the election of directors (the “Outstanding Company Voting Securities”); provided, however, that for purposes of this subsection (A), any acquisition directly from the Company shall not constitute a Change in Control; or

(B) such time as the Continuing Directors (as defined below) do not constitute a majority of the Board (or, if applicable, the Board of Directors of a successor corporation to the Company), where the term “Continuing Director” means at any date a member of the Board (x) who was a member of the Board on the date of the initial adoption of this Plan by the Board or (y) who was nominated or elected subsequent to such date by at least a majority of the directors who were Continuing Directors at the time of such nomination or election or whose election to the Board was recommended or endorsed by at least a majority of the directors who were Continuing Directors at the time of such nomination or election; provided, however, that there shall be excluded from this clause (y) any individual whose initial assumption of office occurred as a result of an actual or threatened election contest with respect to the election or removal of directors or other actual or threatened solicitation of proxies or consents, by or on behalf of a person other than the Board; or

(C) the consummation of a merger, consolidation, reorganization, recapitalization or share exchange involving the Company or a sale or other disposition of all or substantially all of the assets of the Company (a “Business Combination”), unless, immediately following such Business Combination, each of the following two conditions is satisfied: (x) all or substantially all of the individuals and entities who were the beneficial owners of the Outstanding Company Common Stock and Outstanding Company Voting Securities immediately prior to such Business Combination beneficially own, directly or indirectly, more than 50% of the then-outstanding shares of common stock and the combined voting power of the then-outstanding securities entitled to vote generally in the election of directors, respectively, of the resulting or acquiring corporation in such Business Combination (which shall include, without limitation, a corporation which as a result of such transaction owns the Company or substantially all of the Company’s assets either directly or through one or more subsidiaries) (such resulting or acquiring corporation is referred to herein as the “Acquiring Corporation”) in substantially the same proportions as their ownership of the Outstanding Company Common Stock and Outstanding Company Voting Securities, respectively, immediately prior to such Business Combination and (y) no Person (excluding any employee benefit

plan (or related trust) maintained or sponsored by the Company or by the Acquiring Corporation) beneficially owns, directly or indirectly, 40% or more of the then-outstanding shares of common stock of the Acquiring Corporation, or of the combined voting power of the then-outstanding securities of such corporation entitled to vote generally in the election of directors (except to the extent that such ownership existed prior to the Business Combination); or

(D) the liquidation or dissolution of the Company.”

4. Section 4 of the Agreement is hereby amended to add the following Section 4(j):

“(j) Section 409A. This Agreement is intended to comply with the provisions of Section 409A and the Agreement shall, to the extent practicable, be construed in accordance therewith. Terms defined in the Agreement shall have the meanings given such terms under Section 409A if and to the extent required in order to comply with Section 409A. No payments to be made under this Agreement may be accelerated or deferred except as specifically permitted under Section 409A. In the event that the Agreement shall be deemed not to comply with Section 409A, then neither the Company, the Board nor its or their designees or agents shall be liable to the Executive or other person for actions, decisions or determinations made in good faith.

5. In all other respects, the Agreement is hereby ratified and confirmed.

IN WITNESS HEREOF, the parties hereto have executed this Amendment No. 1 to Executive Retention Agreement as of the day and year first set forth above.