We have a virtual SMTP server on premises that is connected to Exchange 365. We are finding that a portion (not all) of the emails in the Queue folder do not get deleted after successfully being sent. This is not a gigantic problem except that recently we had to reboot that system and it sent a bucket load of old and already delivered emails out to recipients when it came back up. Has anyone ever seen this before and do you have any ideas how to fix this? In the past I have certainly seen situations where items get stuck in the Queue because they are not being sent but never when they have already been successfully sent out.