MIME 2018 Proxy Statement

for admittance. You are entitled to attend the Annual Meeting only if you were a shareholder as of 4:00 p.m. (London time) on October 2, 2018, or hold a valid proxy for the Annual Meeting. If you are a shareholder of record, your ownership as of the record date will be verified prior to admittance into the meeting. If you are not a shareholder of record but hold ordinary shares through a broker, trustee, or nominee, you must provide proof of beneficial ownership as of the record date, such as an account statement or similar evidence of ownership. Please allow ample time for the admittance process. For instructions on how to vote your ordinary shares, please refer to the section titled “Voting” beginning on page 1 of this Proxy Statement and the explanatory notes set forth in your enclosed proxy card. A copy of this notice can be found at www.mimecast.com and will be available for inspection at the registered office of the Company from the date of this notice until the date of the Annual Meeting and at the Annual Meeting itself. Shareholders are entitled to appoint a proxy to exercise all or any of their rights to attend and to speak and vote on their behalf at the Annual Meeting. A shareholder may appoint more than one proxy in relation to the Annual Meeting provided that each proxy is appointed to exercise the rights attached to a different share or ordinary shares held by that shareholder. A proxy need not be a shareholder of the Company. The form of proxy, which must be used to make such appointment and give proxy instructions, is included with this Notice of Annual Meeting and Proxy Statement. By Order of the Board of Directors, Robert P. Nault General Counsel and Company Secretary Registered office: 22 Grenville Street St Helier Jersey JE4 8PX Channel Islands Company number: 119119 July 27, 2018 Important Notice Regarding the Availability of Proxy Materials for the Annual General Meeting to be Held on Thursday, October 4, 2018 This Proxy Statement and our Annual Report on Form 10-K for the year ended March 31, 2018 are available for viewing, printing and downloading at www.proxydocs.com/MIME. Our Annual Report on Form 10-K for the year ended March 31, 2018 is also available on the “Investor Relations” section of our website at www.mimecast.com . Alternatively, if you would like us to send you a copy of our Annual Report on Form 10-K, without charge, please contact: Investor Relations at Mimecast Limited 191 Spring Street Lexington, Massachusetts 02421 USA Attn: Robert Sanders, IR Contact Investors@mimecast.com (800) 614-4530 If you would like us to send you a copy of the exhibits listed on the exhibit index of our Annual Report on Form 10-K, we will do so upon your payment of our reasonable expenses in furnishing a requested exhibit.