How do I change smtp port? Or add additional one?

Discussion in 'Installation/Configuration' started by alpha_one, Feb 11, 2011.

  1. alpha_one

    alpha_one New Member


    I follwed the guide for ISPConfig on Debian 6.0.

    I am finished with the installation but i need to change or add the smtp port.

    My isp is blocking 25 so maybe 2525 might be an option? Should I add this as an alternative port or modify 25?

    ..and finally, how do I do this?

    Thank you!
  2. till

    till Super Moderator Staff Member ISPConfig Developer

    If you set a different smtp port then port 25, your server will not receive any emails as the foreign mailserver does not know which port shall be used. So changing the port will not give you a working mailserver.

    If you want to use your server only for outgoing email and dont need to receive any emails, then you can activate the submission port in postfix by removing the # in front of the submission line and restart postfix.
  3. alpha_one

    alpha_one New Member


    I added 587 so for example cellphones can add the smtp. But i still send out on 25 from the server if i understand correct..
  4. vaio

    vaio New Member

    Hello till and alpha_one,
    my ISP is blocking SMTP 25 and how is it possible to sove that outgoing mail can be sent. SMTP from ISP is not good solution since if you use laptop on different ISP's you always need to change that.

    My server is for example: and mail server is (incoming and outgoing - smtp). My ISP has suggested changing port to 465, but if i understand till ok, than it won't work for other servers or what??

    Is smtp port really related to other servers and it won't receive mail?
    Please explain in dumb so newbies can understand.

    Thank you very much!
  5. vaio

    vaio New Member

    I have found solution!

    For all others here it is:

    1. follow Till HOW TO

    2. go to ISPconfig admin section
    3. click System -> Firewall
    4. Add there port 465 and confirm

    This should solve problem of smtp port 25 being blocked by some ISPs.
  6. burice

    burice New Member

    that is exactly my problem! It doesn't matter what port ever i set and use, the outgoing packets will be submitted through the port 25 at last. I t seems what ever I do and what port I set for smtp or smtps, that's just something between client and my server but all of emails from my server to the destination will be sent on port 25. And that's why we all need port 25 for receiving emails because all emails are getting to our servers on port 25 from other servers!
    now what shall all of us do with this matter?!?!?!??! any IDEAS?!
  7. Jesse Norell

    Jesse Norell Active Member

    burice, you cannot get rid of port 25 for main delivery, it is impossible. Port 25 is the well-known port assigned for SMTP, and prescribed in rfc821 (back in 1982). You will have to change where/how you host your email, or get your ISP to remove the packet limit you have on port 25.

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