Most email clients these days offer the ability to utilize the IDLE function of IMAP. What the IMAP IDLE function does is leave a connection open on the mail server, then as soon as a new email has arrived it alerts the mail client and pushes the new message to the client.
In theory this sounds like a very good thing to have configured for your mailbox, unfortunately some problems can occur with the way that Apples Mac Mail handles this function of the IMAP protocol, it seems to leave open multiple IMAP connections instead of just one. Over time they can pile up and become problematic.
So if you're using Mac Mail you might want to think about disabling this specific function to see if it helps, especially if you've received instruction from our support department regarding this..
1. From the Mail drop-down, click on Preferences.
2. Click on Accounts.
3. Select your IMAP account from the list on the left.
4. Click on the Advanced tab.
5. Now disable the Use Idle setting.
That should be all that is necessary in order to go ahead and disable the IMAP IDLE function in your Mac Mail client. This should help ensure that your email client is causing any adverse problems on the server while it's trying to continually synchronize messages.