I have a few users that are experiencing the same issue...
They sit around and wait on a client message, call the client, and when the client resends the message finally arrives.
Some original messages do not arrive for almost 2 weeks afterwards.
The first time this happened, I just assumed that the client was bluffing when they said that they had sent an eMail; perhaps got tied up and “thought” they sent it…
I had been blaming this on the outgoing servers of the senders ISP, but being a recurring problem, and now seeing others with the same issue; it makes me wonder if it may actually be a DH issue.
A support request was placed relating to this issue with absolutely no response.
A nice simple, yes it may be an issue on our end, or no, it is not us but we will monitor would be nice from the DH techs.