I'm configuring a backup server on a local network that has a cable connection. The Cable ISP is filtering all port 25 (smtp) traffic.
uname -a Linux myhost 4.4.0-119-generic #143-Ubuntu SMP Mon Apr 2 16:08:24 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
As a result, my outgoing mail transactions are timing out because (I suspect) the default Postfix configuration is using port 25. (I'm basically using the sendmail command from the shell to send status reports from this server)
I have confirmed I can telnet to port 587 on my destination server:
# telnet myserver.net 587 Trying x.x.x.x... Connected to myserver.net. Escape character is '^]'. EHLO 220 myserver.net ESMTP Sendmail 8.14.7/8.14.7; Mon, 7 May 2018 18:16:08 -0500 (CDT) myhost.net 250-myserver.net Hello hostname [x.x.x.x], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 250-DSN 250-AUTH GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN 250-DELIVERBY 250 HELP
How can I update my Postfix installation so that it uses port 587 AND is compatible with the protocols of the server above? (encryption not needed/required unless it's already supported - don't believe TLS is on this)
I've tried editing /etc/postfix/master.cf and uncommenting this line:
smtpd pass - - y - - smtpd
But I'm still getting timeout errors indicating that it's not using 587. I do not have ufw enabled right now so that is probably not the problem.
I assume there's some additional configuration options I need to postfix?