NDR Codes

Explanation of Codes in Exchange Server 2007

4.2.2

The recipient has exceeded their mailbox limit. 
It could also be that the delivery directory on the Virtual server has exceeded its limit.

4.3.1

Insufficient system resources.  This normally means not enough disk space on the delivery server. 
Microsoft say this Exchange NDR may be reported as out-of-memory error.

4.3.2

A classic temporary problem.  Most likely, the Administrator has frozen the queue.

4.4.1

Intermittent network connection.  The server has not yet responded.  Classic time-out problem.  If it persists, you will also get a 5.4.x status code error.

4.4.2

The server started to deliver the message but then the connection was dropped.  The sending server is configured to retry automatically.

4.4.6

Too many hops.  Most likely, the message is looping.

4.4.7

Problem with a protocol timeout, for example a message header limit.  Check receiving server connectors.

4.4.9

A DNS problem.  Check your smart host setting on the SMTP connector.  For example, check correct SMTP format. Also, use square brackets in the IP address [197.89.1.4]  You can get this same NDR error if you have been deleting routing groups.

4.6.5

Multi-language situation.  Your server does not have the correct language code page installed.

5.0.0

SMTP 500 reply code means an unrecognized address.  You get this NDR when you make a typing mistake when you manually try to send email via telnet.
The most likely cause is a routing error.  One solution maybe to add an * in the address space.
A separate cause for NDR 5.0.0 is a DNS problem.

5.1.x

Exchange 2007 NDR problems with email address.

5.1.0

Sender denied.  Often seen with contacts. Verify the recipient address.
Mismatched Network Card duplex setting.

5.1.1

Bad destination mailbox address.  5.1.1 is the most common Exchange 2007 NDR; there is a problem with the recipient address. 
Maybe the recipient does not exist. 
Possibly the user was moved to another server in Active Directory. 
Check mailbox delegation.
Maybe an Outlook client replied to a message while offline.
Check connector configuration.

5.1.2

SMTP; 550 Host unknown.  An error is triggered when the host name can’t be found.  For example, when trying to send an email to bob@ nonexistantdomain.com.
[Example kindly sent in by Paul T.]

5.1.3

Invalid recipient address.  Another problem often seen with contacts.  Address field maybe empty.  Check the address information.  Or there could be a syntax error.

5.1.4

Destination mailbox address ambiguous.  Two objects have the same address, which confuses the Exchange 2007 Categorizer.

5.1.5

Destination mailbox address invalid.

5.1.6

Problem with homeMDB or msExchHomeServerName - check how many users are affected.  Sometimes running RUS (Recipient Update Service) cures this problem.  Mailbox may have moved.

5.1.7

Invalid address.  Problem with senders mail attribute, check properties sheet in ADUC.

5.1.8

Something the matter with sender's address

5.2.x

NDR caused by the large size of the email.

5.2.1

Mailbox cannot be accessed.

5.2.2

The recipient has exceeded their mailbox storage quota.

5.2.3

Recipient cannot receive messages this big.

5.2.4

Most likely, a distribution list or group is trying to send an email.

5.3.0

Problem with MTA, maybe someone has been editing the registry to disable the MTA.

5.3.1

Mail Server system full.

5.3.2

System not accepting outside network messages. 

5.3.3

Remote server has insufficient disk space to hold email.

5.3.4

Message too big.

5.3.5

System incorrectly configured.  Multiple Virtual Servers are using the same IP address and port.

5.4.0

DNS Problem.

5.4.1

No answer from host. 

5.4.2

Bad connection.

5.4.3

Routing server failure.  No available route.

5.4.4

Cannot find the next hop, check the Routing Group Connector.

5.4.6

Tricky looping problem, a contact has the same email address as an Active Directory user.

5.4.7

Delivery time-out.  Message is taking too long to be delivered.

5.4.8

Microsoft advises, check your recipient policy. SMTP address should be yourdom.com. 
NOT server.yourdom.com.

5.5.0

Underlying SMTP 500 error.  Our server tried ehlo, the recipient's server did not understand and returned a 550 or 500 error.

5.5.1

Invalid command.  (Rare Exchange NDR)

5.5.2

Possibly the disk holding the operating system is full.

5.5.3

Too many recipients.  More than 5,000 recipients.

5.5.4

Invalid domain name.

5.5.5

Wrong protocol version.

5.5.6

Invalid message content. 

5.6.0

Corrupt message content.  Try sending without attachment.

5.6.1

Media not supported.

5.6.3

More than 250 attachments.

5.7.1

A very common Exchange 2007 NDR, the cause is a permissions problem.  For some reason the sender is not allowed to email this account. 
Perhaps an anonymous user is trying to send mail to a distribution list. 
Alternatively, a user may have a manually created email address that does not match a System Policy.
Check SMTP Virtual Server Access Tab.  Try checking this box: Allow computers which successfully authenticate to relay. 
Check the outgoing SMTP logs.
Check: Mailbox - <Mailboxname> - Properties - Mail Flow Settings - Message delivery restrictions.
Try disabling Windows-Integrated-Security.  Instead allow only standard authorization on the SMTP receiver on the Exchange 2007 server.
Check Attachment filtering on the Edge server.

5.7.2

Distribution list cannot expand and so is unable to deliver its messages.

5.7.3

Not Authorized, security problem.  It could be that the sender cannot send to the alternative address.  
On another tack, check external IP address of ISA server. Make sure it matches the SMTP publishing rule.

5.7.4

Extra security features not supported.  Check delivery server settings

5.7.5

Cryptographic failure.  Try a plain message with encryption.

5.7.6

Certificate problem, encryption level maybe to high.

5.7.7

Message integrity problem.