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SMTP not working when following guide on Linode Library
https://forum.linode.com/viewtopic.php?f=11&t=10313
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Author:  Whitey [ Sat Aug 03, 2013 6:01 pm ]
Post subject:  SMTP not working when following guide on Linode Library

Hi guys,

I just followed the awesome guide at https://library.linode.com/email/postfi ... w-it-works and my set up now mostly works. Using Outlook, I can connect to my server via IMAP using my user credentials.

However I'm facing a problem with SMTP. Outlook reports the following error when it tries to send a test email:

Quote:
Send test e-mail message: Outlook cannot connect to your outgoing (SMTP) e-mail server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).


My first thought was to look in /var/log/mail.log, however there's nothing in there relating to SMTP. All it has is my connections via IMAP.

Then, I thought it was a iptables issue. I verified that the port was unblocked and it is via the following rule:

Code:
-A INPUT -p tcp --dport 25 -j ACCEPT


Here's therelevant iptables -L too:

Code:
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:smtp

What's interesting though, is if I try to telnet into my server on port 25 from my Windows machine I get this error message:

Code:
Connecting To <my linode ip>...Could not open connection to the host, on port 25: Connect failed


So it's kind of acting as if the port is blocked even though iptables is reporting it's open.

Does anyone know if there's extra steps I need to take to get SMTP working? I followed that guide line by line and assumed it would work out of the box. Does anyone have any recommendations?

Thank you!

Edit: I also just tried to use port 465 instead of 25 for SSMTP but the exact same problem remains.

Author:  Vance [ Sat Aug 03, 2013 6:38 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

Almost certainly your home ISP is blocking outgoing connections to port 25. Authenticated e-mail should normally be sent using port 587 - make sure Postfix is listening on that port (netstat -lvpnut) and that your firewall allows traffic to that port.

Author:  Whitey [ Sat Aug 03, 2013 6:55 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

My firewall rules do allow port 587, however Postfix doesn't seem to be listening on it according to netstat -lvpnut

Any idea how I can proceed? I'm guessing I need to make Postfix associate port 587 with SMTP?

Author:  Whitey [ Sat Aug 03, 2013 7:00 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

Managed to get it working by following this: http://www.faqforge.com/linux/how-to-en ... n-postfix/

Finally have IMAP and SMTP working completely running from my Linode, huge thanks to whoever wrote that guide on the library!

Author:  mouseowl [ Fri Aug 09, 2013 11:25 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

So I also followed that guide, and am having the same problem. IMAP is working, SMTP is not. The problem is my ISP(along with most peoples ISP) is blocking port 25. I then edited the /etc/postfix/master.cf and uncommented the following lines.

submission inet n - - - - smtpd

and

smtps inet n - - - - smtpd

In theory I should now be able to use SMTP on port 25, 587, and 465 right? However when I configure my account using thunderbird to use port 587, or 465 for SMTP, I get a server timed out error after about 1 min. I have also checked my firewall rules and they are fine. Does anybody have any idea what is going on?

Author:  mouseowl [ Fri Aug 09, 2013 11:36 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

Ok I got it. I told thunderbird to connect on 587 using STARTTLS instead of SSL/TLS and everything worked fine.

Author:  sweh [ Sat Aug 10, 2013 7:59 am ]
Post subject:  Re: SMTP not working when following guide on Linode Library

Right; the submission service is not SSL upon connection; you need to use STARTTLS to tell it to upgrade the channel to encrypted. The smtps port (465) should be SSL if you've done it correct.

Author:  Eric13 [ Wed Sep 04, 2013 3:34 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

Can the library article be updated to include changing from port 25 (enable port 587)? I just followed it and got stuck like many others had in the end. Found a solution in the linked article from faqforge.

Author:  MrsAngelD [ Tue Sep 24, 2013 8:57 pm ]
Post subject:  Re: SMTP not working when following guide on Linode Library

I agree the article should really be updated, I had the same error, which was fixed by following the article linked from http://www.faqforge.com/linux/how-to-en ... n-postfix/

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