I have a user who sporadically incurs latent delivery on his email messages. The recipient gets them 2 weeks later. The messages are sent internally. We are using Trend Micro AV. User has nothing else installed on his workstation. We are using windows 7 profession 64bit. The email messages are not within the user's sent items folder for any of the dates. They are not in the deleted items folder either.
What I have done:
Checked the health center within the admin console of Office 365. There are no alerts for Exchange or any other application. I found the mail items on the date specified by the sender, using the e-discovery tool within Office 365. I was unable to use the mail troubleshooter due to the duration of time that had passed since when the user reported the issue. Instead, I ran message trace which produced info corresponding with what I found using the e-discovery tool. Email messages had been sent and delivered on the dates mentioned.
What can I check? What could the problem be?