I have been struggling with my email shared folders for quite a while now. I always thought the problem is at the server end. After working with my email admin for a few days, we finally found that the problem is related to Thunderbird.
There is a feature called IDLE command support in Thunderbird. If I have this feature turned on, it’s very slow to access the IMAP shared folders. To turn it off, follow these steps.
- Click on Tools -> Account Settings.
- Click on the Server Settings of the affected account and click on Advanced… button.
- Uncheck the box Use IDLE command if the server supports it .