Problem Sending Mail With Postfix

[Paul Schmehl]

--On May 19, 2008 6:07:53 PM -0700 Chuck Swiger <cswiger at mac.com> wrote:

> On May 19, 2008, at 4:17 PM, Montag wrote:
>> host mx1.free.bsd.org said: my.mywebsite.com: Helo command rejected:
>> Host not found (in reply to RCPT TO command))
>> freebsd-questions at freebsd.org
>>
>> Any thoughts?
>
> Many mailservers check that the HELO/EHLO response is a valid hostname.
> You can either configure your machine to use a valid hostname (consider
> dyndns.org or similar, if you like), or you can relay your email to
> something like your ISP's mailserver using relayhost parameter or the
> transport mechanism....

I'm not sure what the point of that is:

Macintosh:~ pauls$ dig +short my.mywebsite.com
208.87.33.150
Macintosh:~ pauls$ dig +short -x 208.87.33.150
my.mywebsite.com.

The site resolves both forward and reverse.  So valid hostname is not the 
problem.

It doesn't seem to be listening on port 25 though.

Macintosh:~ pauls$ telnet my.mywebsite.com 25
Trying 209.181.247.105...
Connected to nullmx.mywebsite.com.
Escape character is '^]'.
Connection closed by foreign host.

Macintosh:~ pauls$ dig +short nullmx.mywebsite.com
209.181.247.105

Which is a bit weird.

Montag, the sendmail commands are all aliased to the corresponding postfix 
commands.  For example, you can check the queue with either sendmail's 
mailq command or postfix's postqueue command.  Both launch the same binary.

Paul Schmehl (pauls at utdallas.edu)
Senior Information Security Analyst
The University of Texas at Dallas
http://www.utdallas.edu/ir/security/