Are you receiving a Bounce back (NDR - Non-Delivery Report) when sending an email message?  We have provided a list below with basic knowlege on what the codes actually mean. You will need to look at the NDR received, view the code to compare it to the list below.



NDR List


4.2.4 - The recipient has exceeded their mailbox qouta.


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


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


5.5.0 - SMTP 500 reply code means an unrecognized address.


5.1.0 - Sender denied. Often seen with contacts. Verify the recipient address.


5.1.2 - SMTP; 550 Host unknown. An error is triggered when the host name can’t be found. 


5.1.3 - Invalid recipient address. Another problem often seen with contacts. Address field maybe empty. Check the address information. 


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.


5.1.8 - Senders address is experiencing trouble.


5.2.1 - Mailbox cannot be accessed. Perhaps the message is too large.


5.2.2 - The recipient has exceeded their mailbox storage quota.


5.2.3 - Recipient cannot receive messages this big. Try resending the message without the attachment.


5.3.4 - The message too large.  Check the limits on both the sender and receiver side. There is likely a policy in operation.


5.4.2 - You may have a bad connection.


5.4.7 - Delivery time-out. The message is taking too long to be delivered.


5.5.3 - Too many recipients. Try resending the same message to fewer recipients.


5.5.4 - Invalid domain name.


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 - The cause is a permissions problem. For some reason the sender is not allowed to email this account.  




If you require further assistance, please submit a ticket to our Support staff.  Please be sure to include the attached headers and original message that was received in text form. Please note that attachments may become encrypted and Support will be unable to review any attached screenshots.