Randomly, at 01h05 in the morning, our Exchange server sends out a number of "not read" message tracking emails. See screen shot. This was brought to my attention by our recruiter. She says it has happened before.
I have also had the odd out of office response from contacts referencing a subject line from a meeting request months ago. So this has happened before and for a period of time. The screenshot below is from meetings approximately 4 months ago.
I personally do not respond to Message Tracking from Outlook. All requests are ignored. I can't be sure of my phone or iPad though.
These are all related to meeeting requests as well.
Windows Server 2008 R2 running as a VM on Hyper V
Exchange 2010 Rolup 5
This has been experienced before by another EE member but was not resolved: