Postfix and SMTP configuration

[kimrru]

I'm extremely new in (albiet excited about) the usage of postfix. What's happening is that when external mail gets sent to our external IP address for SMTP, it does not get delivered and a bounce back ensues. All mail is delivered using our internal IP address. Different email programs have given me different messages. Thunderbird for PC tells me Relay access denied whereas Outlook will simply say that the message was not delivered (thanks for nothing).

Entourage (on a Mac) suggests that "The server may be down, overloaded, or there may be too much net traffic." which is ridiculous because we're a small company with not a lot of emails going out.

Where do I go from here?

Thanks,

Kim

 

[ericbrunson]

Eliminate the mail clients and get directly to the postfix error message:

telnet to the smtp port of the machine with:
telnet mailhostname 25

You should get a banner like this:
220 mail.comfortechassist.com ESMTP Postfix

Converse with postfix like this (lines with numbers are postfix output, you type the rest):

helo comfortechassist.com
250 mail.comfortechassist.com
mail from: <someuser@yourdomain.com>
250 Ok
rcpt to: <avaliduser@yourdomain.com>
250 Ok
data
354 End data with <CR><LF>.<CR><LF>
test
test
test
.
250 Ok: queued as 672BC13FCC
quit
221 Bye

When postfix errors out look in your maillogs and try to correlate the log messages with your error. On my box it's /var/log/maillog, but it's configured in main.cf.