[DebEtch/Postfix/MySQL/Courier: 571 when sending mail (first time)

Hi folks! ;-)

My Server (Debian Etch Box built with Perfect Setup (plus some small modifies I added) with Postfix, Courier, MySQL, Amavis, ClamAV, etc...) is up and happily running since over a month (processing 200 mails per day).

Today I sent an email (it's the first time I send an email to this recipient) with a 128KB PDF Attachment and I received the following response:

Code:

571  MAIL REFUSED - Reverse DNS failed; cannot resolve the
    (perseo.mydomain.tld) domain in the HELO command. (in reply to end of DATA command)

I verified Reverse DNS against www.mxtoolbox.com and got OK.

I think it's not a problem of mine, because it's the first time it occurs in over a month of quiet uptime of the server.

What could it be?

Thanks in advance,
Morenz

 

Please check the reverse DNS like this:

Code:

dig -x [I]1.2.3.4[/I]

where 1.2.3.4 is the IP address of perseo.mydomain.tld.

 

Hi falko and thanks for the reply,
I verified that my server has an outgoing public address of x.x.x.217 (address used by all machines, while the incoming address is NATted by the router on the x.x.x.218, so addresses do not match.

Am I right?

 

Is it a public or a private address? It should be your router's public IP address.

 

yes, they are both public addresses, one (217) is the one we use to access Internet, the other (218) is the one that is assigned to the MX Record of my domain and that the router NATs to the mail server. I have to make an ip nat outside in the router to map the mail server to exit on address 218, not on 217 like all others.

That's what I Suppose...

Good night
Morenz

 

What's in /etc/resolv.conf?

 

Code:

search mydomain.com
nameserver 192.168.1.xxx

nameserver has a private address because we have an internal DNS (2k3 server) that points to ISP DNS.

... another thing I forgot to say: we have 8 static IP assigned.

 

What happens if you use another name server?

 

That DNS points to ISP DNS, should I point directly to that DNS?

Just a question (just because I always use to understand what I'm doing and why): how could a DNS change impact on my problem?

Thanks
Morenz

 

Maybe the name server you're using isn't working properly (or is caching for too long), and that might be the reason why the system can't resolve perseo.mydomain.tld.

 

OK, I will try using the ISP DNS and not the internal one.

Thanks for now, I'll be back to report how did it work.

Regards,
Morenz