Thank you for your feedback.
Today you can see messages which are “pending” in a queue through Message Trace feature. In the Mail flow Dashboard, you can see messages queued for more than an hour. We’ve also created alerting for this condition. Can you tell us what other things you need and what the scenarios look like / how commonly you need to perform the task?
This would help us when evaluating this item further.Anonymous commented
Would also like to have this. Just had an application that's been unable to deliver email for a week which has generated a torrent of undeliverable mail messages which have been sitting in a postifx mail queue. Once I fixed this issue, the postfix queue flushed up to Office 365 and now they're all slowly (100 every few minutes) being delivered to a mailbox in office 365. Wish I could clear whatever internal queue Office 365 has.