Hello Server Geniuses. Im running a full stack email server, dockerized. Having trouble sending email to outlook email addresses. (and only outlook email addresses) I have a theory.
The error I receive is strictly a DNS resolution error
for name=myradar-com.mail.protection.outlook.com type=A: Host not found,
try again
On the server, If I try to test resolve the address, using the command
sudo docker-compose exec postfix-mailcow nslookup myradar-com.mail.protection.outlook.com
I am presented with a timeout error. Once in a while, I'll get a SERVEFAIL error.
If run the exact same command with unbound (also running in the same stack) then it resolves with no problem.
If I try to resolve just the "outlook.com" portion, it works.
I have a theory that Postfix just doesn't recognize a sub.sub.sub.domain.tld as a valid FQDN, and I think its just ignoring the request and not passing it to the resolver at all. I am trying to find "somewhere" in the master.cf or any other config file that instructs postfix on what the correct format of a domain name is, but I am not having any luck. I could also be completely wrong, and maybe something else is wrong (maybe the way postfix is looking for an "A" record for that host???, but then again, unbound works.)
Can anyone help with this issue? or maybe point me in a place to look for an answer?
Edit. I have proved the subdomain levels are not the issue.
