--On Wednesday, June 23, 2021 10:54 PM -0400 H <agents at meddatainc.com> wrote: > Viewing /var/log/maillog I get some information but cannot see which > application generated that e-mail, nor the content of it which would > likely allow me to see where it comes from. > > Can anyone suggest how to track down the app so I can reconfigure the > mail address? Hold all delivery so you can examine the mystery message in the queue. I found this article on how to hold mail with Postfix: <https://serverfault.com/questions/92981/how-do-i-temporarily-suspend-mail-delivery-to-a-specific-domain-non-local-with> This requires creating the file /etc/postfix/hold with a static hold rule and "compiling" it with the postmap command. Add a line to main.cf to use the new map.