Optimum Online, the biggest cable service around here, is blocking trafic on port 25 (standard SMTP port) to reduce spam on their network. This prevents our clients from using our SMTP services. Can our server support two ports for SMTP? We would still use port 25 for clients UNLESS this port is blocked. Then can we have them use an alternate port (like 465) with a secure connection to send?
I went to Webmin -> Servers -> Postfix -> SMTP Authentication And Encryption, following another post. "Enable SASL SMTP authentication" is selected."Enable TLS encryption" is set to "Default". I opened up port 465 in iptables using your most excellent firewall interface, by cloning rule 25 and changing the port. The following test failed:
openssl s_client -connect localhost:465
connect: Connection refused
Any ideas? I did notice that in /etc/postfix/master.cf, the submission line is commented out. Whatever we change, I have to be so very careful. There are currently around 800 email accounts on the system.