Postfix Wont Send Mail
 

I'm having a problem with Postfix sending email. To be more specific, Postfix sends mail perfect but when my web server running webmail (RoundCube) connects to my mail server to send email, it fails & there is nothing in the logs that explain to me why:

When I try sending mail from a client like Thunderbird / Evolution, it works perfect. When I try to send mail from my web server [192.168.0.201], I get a browser error:

SMTP Error: 250 (Authentication Error)

However I don't see a detailed error in /var/log/mail.log as shown above. How can I find out what's causing the error?

My web server [192.168.0.201] is listed in 'mynetworks' for trusted relay. My mail server in question is obviously 192.168.0.200.

Anyone know what I need to do in order to have Postfix give me some info on why my web server can't send mail from webmail?

I often find the best thing you can do to troubleshoot email is to bypass the client and run the session yourself.
Look here for a rough guide on how to do that using TLS: http://qmail.jms1.net/test-auth.shtml
If you run this test from your webserver, the mail server will most likely tell you during the session what the problem is...

You may want to turn on debugging in Dovecot. It has been a while since I have done so, but there are three places/lines where you can enable debugging and verbose logging. This may help.

In case it helps you, I too am using Postfix, Dovecot, with Roundcube mail. I sent a message through Roundcube and captured the log files. I posted them below for you to compare against. One thing that I do notice, but I am not sure if it is the problem or not, is the Anonymous TLS connection. If you notice, my TLS connection is handled a little differently as shown in the first line of the log snippit. I think there may be a postfix setting for "no anonymous". I would also compare against a message sent with your regular mail client and see if there are any differences.

I'm a little confused because Dovecot (IMAP4) is working perfect from both Thunderbird and Webmail (RoundCube) so I would think I would want to debug Postfix for SMTP issues from my web server's incoming IP (192.168.0.201) and not Dovecot, right?

I enabled debugging on Postfix for the 192.168.0.201 IP only and when I try to send email from RoundCube, below is what I get:

Does this explain anything for anyone? I'm curious if I disable TLS on Postfix, would I then be able to send mail or would it still fail? I need to research the 'noanonymous' entry and see if that works or doesn't but from the logs above, it looks like a DNS issue and still not TLS related, right? Thoughts?

Anyone?

Crazy question: is permit_mynetworks listed in "smtpd_recipient_restrictions ="?

Take a look a this discussion thread. I am not sure if it is the same problem you are having, but on the surface at least, it seems to match the symptoms. The thread summary is that they had a timing issue with the DNS that caused a lot of 'no match' statements like in your log, followed by a disconnection due to the timeout. It might make a good test case to relax the some of your recipient / sender restrictions based upon this information. In essence, yes, I agree that it looks like it may be a DNS issue.

Also, the reason I mentioned dovecot debugging is because my initial thought was that you were having an authentication issue with Roundcube mail. This could be caused by things like messed up hashing (e.g. different salt values) that cause passwords to not match or picking up the wrong part of the username.domain string. I now doubt it will help in this case, but it is good to know in case you need this feature.

Yes it is: