When there is an error, the dialog box usually shows itself with the Error tab revealed.
Microsoft has undergone a number of rebrands over the past several years, and it probably would’ve been a good move if their resulting product names weren’t so confusing.
When it is truly stuck (for instance because it is too big), this of course will never work.
In most cases you can see the message and you can use these techniques to remove it.
First Option - Root your mailbox----------------------------------------------Unfortunately, Outlook doesn’t detect this automatically but you can set it manually.
To set the root folder path for your IMAP account:1.
An alternative method would be to set 1-3 “high priority” accounts in a send/receive group which checks for new message every 10 minutes and all the other accounts in a separate send/receive group which checks for new messages every 30 minutes (or even longer)You can set the send/receive interval in; When you have a message stuck in the Outbox, Outlook could end up trying to send that message until it succeeds.Below are some of the steps we have found to improve client performance in Office 365 (Exchange Online) for many of the cases we observed.Important: Some of the information below asks you to make changes to your software and/or usage of them.You shouldn’t set the automatic send/receive interval to less than 5 or even 10 minutes.When you have more than 3 accounts I wouldn’t recommend to set it shorter than 15 minutes.