Hello, We're having problems sending emails to certain users on a domain. At first glance, we thought that the message we were receiving was on their end, but upon further investigation it appears it could be us. Our main IT guy is out today, so I and my other IT co-worker are seeing what kind of progress we can make in his absense. Here is the message we're getting when we send to these users (with certain parts "blanked out" for obvious reasons). Would appreciate any links or tips you can provide. From: System Administrator Sent: Monday, October 08, 2007 11:20 AMTo: Subject: Undeliverable:RE: notebooks Your message did not reach some or all of the intended recipients. Subject: RE: notebooks Sent: 10/8/2007 11:20 AM The following recipient(s) could not be reached: nina@receiving.com on 10/8/2007 11:20 AM You do not have permission to send to this recipient. For assistance, contact your system administrator. <ourmail.ourdomainname.com #5.7.1 smtp;550 5.7.1 <nina@receiving.com>: Recipient address rejected: Mail appeared to be SPAM or forged. Ask your Mail/DNS-Administrator to correct HELO and DNS MX settings or to get removed from DNSBLs; MTA helo: ourmail.ourdomainname.com, MTA hostname: differentmail.ourdifferentdomain.com[XXX.XXX.XXX.XX] (helo/hostname mismatch)>

The receiving server does not clearly say why they block your mail. they just mentiond some reasons. check your DNS A and PTR record to see to see if it mathches your servername for starters.