X0206 3 2021-09-23 0 0001863105 EngageSmart, Inc. ESMT 0000830588 SUMMIT PARTNERS L P 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001514386 Summit Partners Growth Equity Fund VIII-A, L.P. 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001514388 Summit Partners Growth Equity Fund VIII-B, L.P. 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001604887 Summit Partners Entrepreneur Advisors Fund I, L.P. 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001435565 Summit Investors I, LLC 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001494616 Summit Investors I (UK), L.P. 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001627278 SUMMIT MASTER COMPANY, LLC 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001239366 CHUNG PETER Y 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 0001018067 MANNION MARTIN J 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 0 0 1 0 Common Stock, par value $0.001 per share 26926752 I See Footnotes Consists of (i) 19,327,768 shares of common stock held by Summit Partners Growth Equity Fund VIII-A, L.P., (ii) 7,060,848 shares of common stock held by Summit Partners Growth Equity Fund VIII-B, L.P., (iii) 128,222 shares of common stock held by Summit Partners Entrepreneur Advisors Fund I, L.P., (iv) 370,024 shares of common stock held by Summit Investors I, LLC and (v) 39,890 shares of common stock held by Summit Investors I (UK), L.P. Summit Partners, L.P. is the managing member of Summit Partners GE VIII, LLC, which is the general partner of Summit Partners GE VIII, L.P., which is the general partner of each of Summit Partners Growth Equity Fund VIII-A, L.P. and Summit Partners Growth Equity Fund VIII-B, L.P. Summit Master Company, LLC is the (A) sole managing member of Summit Partners Entrepreneur Advisors GP, LLC, which is the general partner of Summit Partners Entrepreneur Advisors Fund I, L.P., and (B) the managing member of Summit Investors Management, LLC, which is the manager of Summit Investors I, LLC and the general partner of Summit Investors I (UK), L.P. Summit Master Company, LLC, as the sole managing member of Summit Partners Entrepreneur Advisors GP, LLC and the managing member of Summit Investors Management, LLC, has delegated investment decisions, including voting and dispositive power, to Summit Partners, L.P. and its Investment Committee. Summit Partners, L.P., through a two-person Investment Committee currently composed of Martin J. Mannion and Peter Y. Chung, has voting and dispositive authority over the shares held by each of these entities and therefore beneficially owns such shares. (Continued from footnote 3) Each of the entities affiliated with Summit Partners, L.P. that are mentioned herein and each of Mr. Mannion and Mr. Chung disclaims beneficial ownership of the shares of common stock, in each case, except to the extent of it or his pecuniary interest therein. /s/ Robin W. Devereux's, as attorney-in-fact for Summit Partners Growth Equity Fund VIII-A, L.P. 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Summit Partners Growth Equity Fund VIII-B, L.P. 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Summit Partners Entrepreneur Advisors Fund I, L.P. 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Summit Investors I, LLC 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Summit Investors I (UK), L.P. 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Summit Partners, L.P. 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Summit Master Company, LLC 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Peter Y. Chung 2021-09-23 /s/ Robin W. Devereux's, as attorney-in-fact for Martin J. Mannion 2021-09-23