LITTLEBLACKDOG.COM

The only thing I've not tried yet is smashing everything with a mace. KB's, support forums, calls with the "experts," have gotten me nowhere.

My client (sender): SBS 2003 with Exchange, Watchguard x15 Edge.
My clients client (recipient): don't know yet.

my client can send and receive mail successfully now to everyone under the sun except for this one firm.

my client can receive mail from this problematic firm, but cannot send to them. Any attempts in sending result in:

Quote:
Your message

To: firstname lastname
Subject: RE:
Sent: Mon, 10 Apr 2006 15:12:50 -0500

did not reach the following recipient(s):
'firstname lastname' on Mon, 10 Apr 2006 15:12:51 -0500
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<our.mailserver.name #5.5.0 smtp;554
<firstnameLastname@recipients.domain>: Relay access denied>

Now, this firms IT dept says "we are blocking anything that comes from an IP that has the word "client" in it's dns resolution. The solution would be to have the sender fix his reverse or send mail via their ISP's SMTP server."

The mail servers reverse, to the best of my knowledge, after several outside tests, does not have "client" in it's reverse IP. All tests I have run kick back h-ip.citylocation.isp.com.

The mail server greeting announces a FQDN.

From multiple locations, I am able to send a mail to both parties using telnet, and tests using SMTPDiag from these same locations are all positive.

Other than SPF, our mail server is common RFC compliant.

MX and A records are correct.
PTR exists and per their IT advise, it does not (and never did) contain "client."

Any ideas?

Posted: Tue Apr 11, 2006 8:32 am Post subject:

client's client has a misconfigured rule file, or client is connected privately, perhaps, to client's client and because of this the SMTP server (any idea what server?) thinks it's a relay.

It's one scenario. A proper mail log from the downstream rejecter would be useful.

Posted: Tue Apr 11, 2006 8:52 am Post subject:

EdisonRex wrote:
client's client has a misconfigured rule file

was my feeling

EdisonRex wrote:
or client is connected privately, perhaps, to client's client and because of this the SMTP server (any idea what server?) thinks it's a relay.

thought crossed my mind too. SMTP via Telnet and SMTPDiag all work fine though. So taking our Exchange out of the loop makes me scratch my head a little. After running through Exchange 100 times, I find nothing out of the ordinary. Nothing at all that would suggest that we are trying to relay messages through their server at least.

Don't know what the server is yet. I have placed two calls into their IT guy, no return call yet.

EdisonRex wrote:
A proper mail log from the downstream rejecter would be useful.

aye... as would a phone call back from their IT guy.