Could be also greylisting ,but I found this : Problem: When you send an email, you receive a 4.4.7 error message: Non-Delivery Receipt (NDR) message
Solution: A 4.4.7 NDR message usually indicates a problem on the receiving server; check the validity of the recipient's address. You can also perform an MX <http://www.123together.com/Support/lookup_mx_record_dns_domain.htm> lookup <http://www.iptools.com/> on the receiving domain to determine if the receiving server is configured to receive messages correctly. A 4.4.7 NDR message can also indicate that a message header limit has been reached on a remote server or that some other protocol timeout has occurred while communicating with the remote server. It may be necessary to reduce the number of recipients in the header of the message for the host to which you are receiving this error. If you then resend the message, it is placed in the queue again, and if the receiving server is up, the message is delivered. An example of the typical bounce-back NDR message is shown below: -----Original Message----- From: System Administrator Sent: DateTime To: 'Recipients_Name' Subject: Undeliverable: Subject_Of_Original_Message Your message did not reach some or all of the intended recipients. Subject: Subject_Of_Original_Message Sent: DateTime The following recipient(s) could not be reached: 'Recipients_Name' on 3DateTime Could not deliver the message in the time limit specified. Please retry or contact your administrator. <FQDN_Of_Sending_Server#4.4.7> GuidoElia HELPPC _____ Da: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Inviato: giovedì 20 novembre 2008 23.26 A: MS-Exchange Admin Issues Oggetto: Weird NDR issue Hi all, I have two exchange 2003 systems in a AD integrated environment. Both are running on 2003 entrprise edition. The second server handles the stores and user delivery. The primary server is an older server and pretty much just acts as a fetchmail server for external POP accounts and an archive store. The flow runs as such. Incoming mails are pulled in by Server A and then delivered to the stores on Server B. The users use Outlook 2007 (Upgraded from 2003) on Windows XP. Since there are users for the domain on the exchange server and a lot of users that get their mail from the ISP mail server, I have a Exchange connector setup to deliver unknown e-mail to the ISP's mail server. This has been working great for the last three years, however we started get a lot of NDR's for a couple of users now. The messages are stuck in the Exchange connector queue. and have hundreds of retries. I turned on level 7 debugging on the SMTP server on both systems, but I don't see any related errors or any attempts to deliver the message. I watched the logs on the ISP's mail server and nothing showed up related to that message. This is the NDR that comes back. Could not deliver the message in the time limit specified. Please retry or contact your administrator. <server.domain.com #4.4.7> Users are starting to get very angry that this is happening. I have tried to force the queue to connect, but the messages don't do anything until they time out or I kill the messages. It is usually no more than 3-4 messages that have this issue. The e-mail have either been external customers or employees that live on the other server. Any help would be appreciated. ~ Ninja Email Security with Cloudmark Spam Engine Gets Image Spam ~ ~ http://www.sunbeltsoftware.com/Ninja ~
