Postfix Mail Queue Not Processing on CentOS 7 with Misconfigured Transport Maps
I'm trying to implement I'm collaborating on a project where I'm working through a tutorial and I'm relatively new to this, so bear with me. I'm working with an scenario where my Postfix mail queue on CentOS 7 is not processing emails, and I suspect it might be due to misconfigured transport maps. The configuration is set up to route emails for a specific domain through an external SMTP server, but the emails just sit in the queue. I checked the mail logs and found the following behavior message: ``` Oct 10 18:30:01 myhost postfix/qmgr[12345]: 1234ABCD: from=<user@example.com>, size=1234, nrcpt=1 (queue active) Oct 10 18:30:01 myhost postfix/smtp[12346]: 1234ABCD: to=<recipient@external.com>, relay=none, delay=1, delays=0.01/0.01/0.00/0, dsn=4.4.1, status=deferred (connect to external.smtp.server:25: Connection timed out) ``` In my `main.cf`, I have the following settings: ```bash relayhost = [external.smtp.server]:25 transport_maps = hash:/etc/postfix/transport ``` And in my `transport` file, I have defined the routing like this: ```bash example.com smtp:[external.smtp.server] ``` After making changes to the transport file, I ran `postmap /etc/postfix/transport` and restarted Postfix. However, the connection still times out. I've verified that the external SMTP server is reachable using telnet: ```bash telnet external.smtp.server 25 ``` This command succeeds, but I still need to send mail through Postfix. I also checked firewall rules using `firewall-cmd --list-all`, and it appears that port 25 is open. I tried increasing the logging level in Postfix to see if I could get more insight, using `postconf -e 'debug_peer_list = external.smtp.server'` and restarted Postfix again, but the additional logs aren't showing anything helpful. What could be causing this scenario with the transport maps and the email queuing? Is there anything else I should check or configure? Cheers for any assistance! Thanks for your help in advance! Thanks for your help in advance! This is happening in both development and production on Windows 10. Any advice would be much appreciated.