OWA: In most tries will get timeout error 500 and open it within 2 seconds after hitting refresh, after the error. Sometimes won't open at all. Will open that mailbox if I use different credentials beforehand and work for some time.
So far: Have tried on different PC, not PC related. His mailbox will not function properly on any other PC. Tried to give myself fullAccess on his mailbox, results - my outlook hangs. Same goes for OWA on different PC.
Sometimes it works just fine, but that's maybe 10 minutes a day. My mailbox is on same DB and it works perfectly, there are ~50 other mailboxes on it actually.
Permissions are fine and inherited. Tried disable/enable mailbox, seemed like it resolved issue for half an hour. Might be just coincidence.
So far I have not found anything related in logs.
Yesterday I tried to fix this. I created new user, created new mailbox, exported old mailbox to PST, imported PST to his new mailbox. Mailbox stopped working.
I've tried "New local move request" with "skip the mailbox if corrupted messages are found", it moved without any issue.
Item count is 22k and ~10 folders, no archive. And there are at least 3 "heavy" users with over 200k item count and tons of folders.
What actually happens. Can't access OWA for at least 45 minutes every hour, Outlook would not be able to connect, would get message "outlook trying to retrieve data from mailserver..."
Extracted mailboxFolderStatistics - user got Restriction parameter on every folder.
Example: SearchFolders : {Restriction(1-33BEE76D), AllItems, Text Messages, חיפוש משימות לביצוע, עיבוד דואר
new-mailboxrepairRequest returns no error in mailbox, with all available flags.