I'm running exchange 2013 with CU7. Sporadically, I have different users complaining that they are not receiving external email.
I also sent a few test messages from my personal email accounts, and in fact, they don't arrive, sometimes until hours later or next day.
So I have one user in particular now that is experiencing this issue.
I looked at the queue viewer, then queues, but it's worthless, as it doesn't tell me anything.
Are there any steps, or what can I do to identify the problem?