MIME 2018 Proxy Statement

PROXY STATEMENT FOR THE 2018 ANNUAL GENERAL MEETING OF THE COMPANY TO BE HELD THURSDAY, OCTOBER 4, 2018 GENERAL INFORMATION Our Board of Directors (the “Board”) solicits your proxy on our behalf for the 2018 Annual General Meeting (the “Annual Meeting”) of Mimecast Limited and at any postponement or adjournment of the Annual Meeting for the purposes set forth in this Proxy Statement and the accompanying Notice of 2018 Annual General Meeting of Mimecast Limited (the “Notice”). The Annual Meeting will be held at 10:00 a.m. (London time) on Thursday, October 4, 2018, at our offices, located at City Point, One Ropemaker Street, Moorgate, London EC2Y 9AW, United Kingdom. We are mailing this Proxy Statement to shareholders beginning on August 22, 2018. In this Proxy Statement the terms “Mimecast,” “the Company,” “we,” “us,” and “our” refer to Mimecast. In this Proxy Statement the terms “members”, “shareholders” and “you” refer to the holders of ordinary shares in the capital of the Company. The mailing address of our principal executive offices is Mimecast Limited, City Point, One Ropemaker Street, Moorgate, London EC2Y 9AW, United Kingdom. Availability of Proxy Materials . . . . . . Beginning on August 22, 2018, we will mail the Notice and Proxy Statement and a proxy card to shareholders. These proxy materials contain instructions on how to vote. We have also enclosed our Annual Report on Form 10-K for the year ended March 31, 2018, which contains, among other things, our audited consolidated financial statements for the year ended March 31, 2018. This Notice and Proxy Statement and our Annual Report on Form 10-K for the year ended March 31, 2018 are also available for viewing, printing and downloading at www.proxydocs.com/MIME. Record Date . . . . . . . . . . . . . . . . . . . . . . 4:00 p.m. (London time) on October 2, 2018 (the “Record Date”). You are entitled to vote only if you are a shareholder of the Company at 4:00 p.m. (London time) on the Record Date. Quorum . . . . . . . . . . . . . . . . . . . . . . . . . At least two shareholders representing between them not less than one third of the ordinary shares in issue as of the Record Date shall constitute a quorum. Ordinary Shares Outstanding . . . . . . . There were 59,668,182 ordinary shares outstanding as of July 25, 2018. Voting . . . . . . . . . . . . . . . . . . . . . . . . . . . There are three ways a shareholder of record can vote: (1) By Telephone: You can vote by telephone by following the instructions in the proxy materials. (2) By Mail: You can vote by mailing your proxy card as described in the proxy materials. (3) In Person: If you are a shareholder as of the record date, you may vote in person at the Annual Meeting. Submitting a proxy will not prevent a shareholder from attending the Annual Meeting, revoking their earlier-submitted proxy, and voting in person. 1