Knowledgebase

 internet access providers have port 25 disabled in their routers to prevent spam. If you run your own mailserver you want to add submission port (587) in postfix to be able to send emails from local email client to the mailserver.

To enable port 587, edit the file /etc/postfix/master.cf

vi /etc/postfix/master.cf

and remove the # in front of the line:

#submission inet n – n – – smtpd

so that it looks like this:

submission inet n – n – – smtpd

or if the line is missing add the above line

and restart postfix:

/etc/init.d/postfix restart