I had a problem for over a year now with a mail account hosted on my ispconfig server.
The first thing I noticed was that there was a phantom folder with no name under my email account.
Then after it performed a Send and Receive, Outlook would crash.
It turns out that there was a bug in ispConfig 220.127.116.11 that inserted a extra line break in the Mail Subscription file. Even though I was running 18.104.22.168, my email was created while in the previous version.
Remove the first line and save. :qw