Thank you, Stefano for the quick feedback.
From experience with 3rd party add-ons/plugins, they vary in stability. for example (Outlook CalDav Synchronizer) for windows has been our go-to application for a while, now with the latest package release, it added some features that delete old entrees and has decided to remove everyone's calendar entries. This is a localized case so could still be down to user error and of course, we would point the client away from Outlook if possible but as you will know it's hard these days with outlook dependent apps and the marketing of Windows.
May I ask what the reasoning is to forget about ActiveSync? While testing standalone versions of SOGo/Samba4 that have this feature I have grown to like it myself
. Happy to be convinced otherwise.