X0306 4 2020-10-08 0 0001644675 Mimecast Ltd MIME 0001735938 Ward Stephen M C/O MIMECAST NORTH AMERICA, INC. 191 SPRING STREET LEXINGTON MA 02421 1 0 0 0 Restricted Share Units 2020-10-08 4 A 0 3720 0.00 A 3720 D Ordinary Shares 12873 D Restricted Share Units 2362 D Each restricted share unit represents a contingent right to receive one share of the Issuer's ordinary shares. These restricted share units were granted on October 8, 2020 and vest in full on the one year anniversary of the date of grant, provided that the Reporting Person remains a director of the Issuer on such vesting date. These restricted share units were granted on January 2, 2018 and 2,361 units vested on January 2, 2019, 2,361 units vested on January 2, 2020 and 2,362 units vest on January 2, 2021, provided that the Reporting Person remains a director of the Issuer on such vesting date. Exhibit 24 Power of Attorney (incorporated by reference to Power of Attorney filed as Exhibit 24 to Form 3 filed by the Reporting Person on January 2, 2018). /s/ Robert P. Nault, Attorney-in-Fact 2020-10-09