We changed internet service providers from "logix" to "windstream". Logix has completely deleted us. Windstream has changed our "mx record".
Almost all of our customers are sending/receiving email from us without issue.
However there are a few that are getting kick backs when sending us email.
The kick back message indicates that they are trying to go through the previous "logix" server. I had them delete the email address from their address book and set it up again. And they still get the kick back referencing the "Logix" server.
Contacted Logix and they said all routing to them has been deleted.
Contacted Windstream and they said all is right on their end including the "mx record".
For this reason I believe that "logix" is somehow embedded in the senders address book for this email address via their mail server.
The domain name for the email addresses did not change. The location of the domain did change and obviously all is right in this world as most of the emails are coming/going as they should.
Attached is a copy of the kick back.