I use Outlook with my Office 365 subscription and have an IMAP email account with Godaddy. On my desktop computer Outlook will "hang" almost daily while synchronizing the IMAP folders. I have to reboot the computer to fix the issue. I have gotten online with Microsoft support several times and have done the following:
1. Reduced the number of emails in my Inbox
2. Reduced the subscribed folder list so that the synchronizing is only for Inbox, Deleted, Drafts, Bulk, Sent, etc. Incidentally, I have to do this step over and over. I am not sure why it will not keep these settings.
So far nothing seems to work with Microsoft so the tech there suggested maybe it is a problem with my hosting server. I am reaching out to see if anyone else has this problem.
I had about 20 folders set up so I could keep emails separated by client. Since the subscribed folders setting would never remain applied to only the Inbox, Sent, etc., I archived every other folder thinking that would fix the sync problems. It worked for about 4 days, and now I have had to reboot twice today already to get my email working. Curiously I can send emails while having the sync problem but not receive. I can also get emails on my phone and my tablet just not on my desktop computer.
After a third attempt with Microsoft support, I believe the issue has been resolved - at least temporarily. I use F-Secure for my virus software, and there was a setting called "Web traffic scanning" that was the culprit. After disabling that feature I have not had the problem reoccur. BUT, I also archived most of my Sent folder which was the only folder not previously archived. See if your virus software has a setting similar to F-Secure and disable it.