Problem Sending Mail With Postfix

[Paul Schmehl]

--On May 19, 2008 10:15:25 PM -0400 Sahil Tandon <sahil at tandon.net> wrote:

> On May 19, 2008, at 4:17 PM, Montag wrote:
>
>> host mx1.free.bsd.org said: my.mywebsite.com: Helo command rejected:
>
> Are you sure it wasn't mx1.freebsd.org?  And are you mangling
> my.mywebsite.com or is that really the hostname with which your server
> is  configured to EHLO/HELO?  The FreeBSD MXs also run Postfix and
> employ the  reject_unknown_helo_hostname restriction; it rejects HELO
> and EHLO hostnames  that lack DNS A or MX records.  Your log excerpt
> looks suspicious because  my.mywebsite.com does have a valid DNS A
> record:
>
> 	my.mywebsite.com.	96	IN	A	208.87.33.150

Yes, but this is a bit weird.

Macintosh:~ pauls$ telnet my.mywebsite.com 25
Trying 209.181.247.105...
Connected to nullmx.mywebsite.com.
Escape character is '^]'.
220 nullmx SMTP
EHLO testing.mydomain.com
220 Hello
quit
220 Buh-bye!
Connection closed by foreign host

Why "nullmx.mywebsite.com"?  Which resolves to an entirely different IP 
address.

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

But it *is* the MX for that domain.

Macintosh:~ pauls$ dig -t MX mywebsite.com

; <<>> DiG 9.4.1-P1 <<>> -t MX mywebsite.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49578
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3

;; QUESTION SECTION:
;mywebsite.com.			IN	MX

;; ANSWER SECTION:
mywebsite.com.		300	IN	MX	10 nullmx.mywebsite.com.

So I've got no idea why he's having this problem, unless it's because the 
MX record doesn't point to my.mywebsite.com.

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