Some domains do not receive emails from our domain

Is the ip address of the server reponsible for sending email outbound registered on a internet DNS with your outbound domain name? If not, this might give problems when a spam filter does a reverse lookup.

I would check to see if I'm on any blacklists.  I ran into a problem similar to yours and lo and behold, I was blacklisted on a couple servers because I was once an open relay.  I would check two sites to verify since some sites can give a false-positive.


www.dnsgoodies.com
www.mxtoolbox.com

I suppose it's a malformatted disclaimer set on eTrust SCM... We're not in the blacklist. I check it at least twice a week. I will write back after modifying it to see if it worked.

OK. I've set up a proper format (I think it's proper) for disclaimer in CA SCM and some messages now pass through, though there're still some domains that don't receive emails...
I've made a test with telnet client to send email and I've noticed that when I send email from telnet message arrives with the strange From: field which says "derived from envelope by postmaster@mail-mx-3.tiscali.it <email@address.com>".

instead of email@address.com there's my real e-mail address. Can this be the reason?

This was not actually a problem... Fixing disclaimer resolved most issues but still we have this problem, although with less recipients.

When emails are routed through our local SMTP, let's say 10.10.1.1 where is our ISA and eTrust SCM installed, we sometimes get the error report from SCM that says as follows:

---------------------------------------------------------------------------------
eTrust Secure Content Manager SMTPMAIL could not deliver the e-mail below because of unreachable host Please check the recipients e-mail address before you try again:
recepient_address

Original message header:
=======================================

X-eSCM-MailFrom:"exchange_user_email_address"
X-eSCM-FileID: smtp_4874D255_614A_0000.oub
Received: from 10.10.1.1 (10.10.1.1)
      by mail.companyname.it (10.10.0.10);
      Wed, 09 Jul 2008 16:59:33 +0200
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: multipart/mixed;
      boundary="----_=_NextPart_001_01C8E1D4.653D8F8E"
Disposition-Notification-To: "exchange_user_email_address"
X-MimeOLE: Produced By Microsoft Exchange V6.5
Subject: I: Subject
Date: Wed, 9 Jul 2008 16:59:32 +0200
Message-ID:
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator:
Thread-Topic: Subject
Thread-Index: AcjhD4I6JFOQCfb2R6myqpLbXK8V3wAxOBaA
From: "exchange_user_email_address"
To: "recipient_email"
---------------------------------------------------------------------------------


So, in this case I have to add domain of the recipient to the address space under exchange server connector (which points to our ISP smtp). In this case emails that generated error as above go out and are successfully delivered.
My problem is to find out the reason why some domains fail to receive emails from our local SMTP but receive emails when routed through provider's SMTP.
Is there a way to troubleshoot that?

Thanks!