I've read other posts regarding this, but there seems to be no solution given publicly, just through private messages or whatever.  I recently added DKIM and DMARC entries to my DNS to improve my "spam" score using mail-tester.  The first legit email I tried to send after that and my support email is immediately "blocked".  I attempted to contact Zoho, and was told that my domain/IP was listed by "a few 3rd party real time blacklists", of which no exact blacklists were given. I've used 5 or 6 different tools for running my domain/IP against blackslists and have found 0 as "listed" or "blacklisted".  If my domain/IP was blacklisted, why is JUST this single email disabled/blocked? I can send from other emails on my domain just fine.  I did find another post from Zoho on a thread for a user with a similar problem, and that post contained the exact message, verbatim, as the reply I got already.  The blocked email is my support email, and I have no way of replying or sending messages to my customers until it's unblocked.

The original message was:

Subject: User Blocked [support@mydomain.com]

Message: "Details :User marked as SPAMMER. Mail Fetch has also been disabled for any active POP accounts."