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randy
Asked: 2013-12-10 13:15:48 +0800 CST

changing port on sendmail and checking it to make sure it works

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I am using smart_host and it(mail.myotherdomain.com) is listening on PORT 26

I have put these two lines in my /etc/mail/sendmail.mc

define(`SMART_HOST',`mail.myotherdomain.com')dnl
define(`RELAY_MAILER_ARGS', `TCP $h 26')dnl

I then do 

make -C /etc/mail
service sendmail restart

Is there a way to verify that it is actually using port 26?

Thanks

sendmail

2 Answers

  1. You can try to telnet to the box, using port 26.

    telnet localhost 26

    Then, issue some SMTP commands to test.

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  2. First, ensure something is listening on port 26:

    $ sudo netstat -tunlp | grep 26

    Then, if there is, from another host on your network, try and connect via telnet:

    $ telnet <IP_address> 26

    If sendmail answers, you're good.

    BUT

    Why do you want to do this? The email transport system is fairly rigid with regards to what ports SMTP happens on, and if you want a prayer of being able to interact with other mail systems, you have no choice but to have your MTA listening on port 25.

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