EarthLink (ELNK) 10-K 2005 FY Annual report

Exhibit 32.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report on Form 10-K of EarthLink, Inc. (the “Company”) for the year ended December 31, 2005 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Charles G. Betty, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, to my knowledge that:

(1)the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/Charles G. Betty

Charles G. Betty

Chief Executive Officer

March 16, 2006