said by NyQuil Kid:... I suspect that for some reason Comcast is flagging provest.us - is this possible ...
Of course it is. The sender's mail admin should check their mailserver logs to ensure Comcast is actually accepting email from them and, if not, why not.
Trivial to do for a half-way competent email admin where half-way decent email server software is used.
If Comcast is rejecting provest.us' email, provest.us' systems
should be notifying the sender(s). If they're not: They're broken.
If Comcast's servers are accepting the email, and the recipient isn't seeing it, that would tend to indicate Comcast may dropping it on the floor somewhere. Can't say as I've heard of Comcast normally being guilty of doing that.
Exception to the above: Comcast accepts, rejects internally, sends a bounce back to the sender, sender refuses the bounce notification or accepts it and drops it on the floor (neither of which they should do). The email would
appear to have disappeared w/in Comcast's network when, in reality, it did not. (Lacking cooperation from Comcast's mail admins, where busy servers are involved, determining this is happening can be neigh impossible, due to the relative impossibility of relating bounced outgoing email with [delayed] bounce notifications.)
Executive summary: Email delivery is not reliable, and the non-delivery notification mechanisms are no better. This is primarily due to three things: Email abuse creating a hostile environment, poorly-written software, and incompetent email admins.
Jim