How do I set up SMTP on port 587

Posted January 30, 2015 10.9k views

I am using POSTFIX and Dovecot and have the incoming email working OK. Also outgoing via mail or sendmail works OK. But I can’t seem to get Thunderbird on my home computer to connect with the server on port 587 (or 25 for that matter). I have tried telnet and also did an nmap which showed these ports open:
Discovered open port 80/tcp on
Discovered open port 143/tcp on
Discovered open port 8080/tcp on
Discovered open port 995/tcp on
Discovered open port 993/tcp on
Discovered open port 110/tcp on
Discovered open port 22/tcp on

Gut no 587 or 25. What am I missing?

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1 answer

Since neither is open, I’m going to take a stab in the dark and say postfix isn’t running.

service postfix start

  • I had to edit /etc/postfix/ and add
    submission inet n - - - - smtpd
    -o syslogname=postfix/submission
    -o smtpd
    -o smtpdsaslauthenable=yes
    -o smtpd

    That opened port 587 but I am still having problems getting the send side in Thunderbird to work. Getting email to work all the way around is pretty complicated between postfix and dovecot.