X0306 4 2018-09-11 0 0001644675 Mimecast Ltd MIME 0001328837 Lieberman Jeffrey C/O INSIGHT VENTURE PARTNERS 1114 AVENUE OF THE AMERICAS, 36TH FLOOR NEW YORK NY 10036 1 0 0 0 Ordinary Shares 2018-09-11 4 J 0 10073 A 10073 D Ordinary Shares 2018-09-11 4 J 0 995708 D 8512044 I See footnotes See Exhibit 99.1 See Exhibit 99.1 See Exhibit 99.1 See Exhibit 99.1 See Exhibit 99.1 Exhibit 99.1 - Explanation of Responses /s/ Jeffrey Lieberman 2018-09-13