My advice is to use MAPI/EWS with Outlook 2016/2019/365.
It works really a lot better and you don't have to waste an EAS license.
EAS is more suitable to Smartphones.
Gabriele Maoret - Head of SysAdmins at SERSIS
Currently manages 6 SmarterMail installations (1 in the cloud for SERSIS which provides services to a few hundred third-party email domains + 5 on-premise for customers who prefer to have their mail server in-house)