Postfix as gmail relay
by Timothy Miller from LinuxQuestions.org on (#4YQ7F)
So, never set up new email servers before, so this is the first time I've ever worked with postfix. Trying to set it up to be a gmail relay for all our internal servers to use for notifications. Existing is a very aged Win2008r2 server that started with the company 5 years before I did. New server is a fully updated CentOS 8 install.
I've got all the authentication set up, and using the mail command can successfully send email from the server itself through the relay, so that works.
netstat shows postfix (well, master, but postfix) listening on port 25
Quote:
only changes I made to main.cf were adding the lines needed for the relay and chaning the TLS level to make sure that it always uses TLS when sending
Quote:
The issue is that when I test from another server it fails. I'm sending on port 25, no authentication (most of the software doesn't support authentication). I see nothing in journalctl or /var/spool/maillog from the relay that there was an attempt to contact it.
I have set selinux to permissive and deactivated firewalld to test if either of those were blocking postfix from listening, but still fails. Not sure where else to check...
I've got all the authentication set up, and using the mail command can successfully send email from the server itself through the relay, so that works.
netstat shows postfix (well, master, but postfix) listening on port 25
Quote:
| [root@azphxlsgmrelay ~]# netstat -pltn Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name <snip> tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 2438/master tcp6 0 0 ::1:25 :::* LISTEN 2438/master |
only changes I made to main.cf were adding the lines needed for the relay and chaning the TLS level to make sure that it always uses TLS when sending
Quote:
| smtp_tls_security_level = encrypt smtp_use_tls = yes smtp_sasl_auth_enable = yes smtp_sasl_security_options = smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd |
The issue is that when I test from another server it fails. I'm sending on port 25, no authentication (most of the software doesn't support authentication). I see nothing in journalctl or /var/spool/maillog from the relay that there was an attempt to contact it.
I have set selinux to permissive and deactivated firewalld to test if either of those were blocking postfix from listening, but still fails. Not sure where else to check...