unfortunately this problem occurred to a senior executive of an important client of mine...
So I couldn't wait and had to try to solve the problem as quickly as possible.
SUMMARY:
I was on build 8930 and everything worked (apart from the small bugs already known about this version) --> I switched to the "new" 9008 and after a few days the problem appeared --> I then updated to 9014, but the problem persists.
In the end I went back to the "old" (pre Linux, so to speak) 8930 and now everything works fine (the small bugs of this version are, all in all, bearable...)
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)