When you have many folders with many messages in Microsoft Outlook, synchronization can be slow or even appear to hang.
Outlook hangs because it downloads all messages every time, including attachments, while with a regular email IMAP application, only headers are being synced.
To solve this issue in Outlook, please follow these steps:
Open Outlook as usual and right-click on your email account and select “IMAP Folders…”
1. Click on the “Subscribed” tab and click the “Query” button.
2. Select all items in the list as follow:
3. Select the first item in the list and scroll down.
4. Hold shift and click the last item in the list.
5. Click the “Unsubscribe” button on the right.
You may get prompted about folders that cannot be unsubscribed, click “OK” here.
6. Next, select the “ALL” tab as we are now going to sync folders we wish or need to sync.
7. Select “Drafts” and click subscribe.
8. Select “Inbox” and click subscribe.
9. Select “Spam” and click subscribe.
10. Select “Sent” and click subscribe.
11. Select “Templates” and click subscribe.
12. Select “Trash” and click subscribe.
Do this for any other folders you wish to sync with the server.
The steps above should resolve the issue of Outlook hanging on “Fix Outlook hangs on synchronizing subscribed folders.”