Hi Roger!
I'm having the same problem you reported regarding calendars: some users who use EM Client (EWS accounts) and MS Outlook (MAPI Exchange accounts) have noticed that the appointments they mark in their calendar are NOT being saved on the SmarterMail server (nor are invitations to other users...).
The worst thing is that when you resync the client, the created appointments simply disappear.
Downgrading to 9392 (because it was my previous working version, never tried 9400...) solves the problem, but the appointments must be recreated from scratch...
Gabriele Maoret - Head of SysAdmins and CISO 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)