EXHIBIT 8.1 September 23, 1999 DoubleClick, Inc. 41 Madison Avenue, 32nd Floor New York, NY 10010 Ladies and Gentlemen: This opinion is being delivered to you in connection with (i) the Agreement and Plan of Merger and Reorganization (the "Agreement")...Agreement and Plan of Merger and Reorganization • September 23rd, 1999 • Doubleclick Inc • Services-advertising
