Exhibit 32

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

The certification set forth below is being submitted in connection with the Quarterly Report of International Paper Company (the “Company”) on Form 10-Q for the quarterly period ended March 31, 2024 for the purpose of complying with Rule 13a-14(b) or Rule 15d-14(b) of the Securities Exchange Act of 1934 (the “Exchange Act”) and Section 1350 of Chapter 63 of Title 18 of the United States Code. Mark S. Sutton, Chief Executive Officer of the Company, and Timothy S. Nicholls, Chief Financial Officer of the Company, each certify that, to the best of his or her knowledge:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) of the Exchange Act; 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/ Mark S. Sutton

Mark S. Sutton

Chairman of the Board and Chief Executive Officer

April 26, 2024

/s/ Timothy S. Nicholls

Timothy S. Nicholls

Senior Vice President and Chief Financial Officer

April 26, 2024