Exchange 2003 Ent - Outlook 2003 One the users is getting the following message when he tries to send an email to an external email address. The emails goes through without a problem to other external domains like @gmail.com or @hotmail.comWe don't scan outbound email traffic just the inbound one. The message Tracking center shows that the message was not delivered to the @domain.edu address. These are the two last messages I get about the delivery. SMTP:Started Outbound Transfer of MEssageSMTP: Non-Delivered Report (NDR) GeneratedThis is the NDR that the users gets. The following recipient(s) could not be reached: user@domain.edu on 1/13/2010 9:44 AM You do not have permission to send to this recipient. For assistance, contact your system administrator. <EXCHANGE.domain.Local #5.7.1 smtp;550 5.7.1 Message rejected as spam by Content Filtering.>

You'll have to contact the postmaster/email admin at the recipient domain to get it sorted out.

I have checked for RBL problems via DNS Stuff and ALL the results are fine.

Well...I just found that they are blacklisted SPAMCANNIBAL 127.0.0.2 "blocked, See: http://www.spamcannibal.org/cannibal.cgi?page=lookup&lookup=136.204.34.83" http://www.spamcannibal.org/cannibal.cgi Will that prevent my SMTP server to send emails to their smtp server?

Their being blacklisted shouldn't stop you from sending them email, if anything it would stop you from receiving mail from them.I'd give them a call. I'd say there's a good chance they've implemented some new anti spam procedures as a result of being blacklisted, and they need to do some tuning. .edu domains are notorious for being sources of spam, so I'm not surprised they're blacklisted. The students plug up their brand-new laptops (sans AV) to the school network, and pretty soon they belong to somebody's botnet.

Can anyone help us on this ? Your message did not reach some or all of the intended recipients. Subject: TEST from OE Sent: 2/14/2012 12:21 PM The following recipient(s) could not be reached: Chris.Leung@yellowpages.com.sg on 2/14/2012 12:21 PM You do not have permission to send to this recipient. For assistance, contact your system administrator. <empower.oneloyalty.com #5.7.1 smtp;550 5.7.1 Service unavailable; Client host [203.126.180.80] blocked using Blocklist 1, mail from IP banned; To request removal from this list please forward this message to delist@messaging.microsoft.com.>