IT Services

Interpreting failed-delivery reports


Occassionally, Nexus may reject a message that you send and return a report of a failed delivery such as the following:

Delivery has failed to these recipients or distribution lists:

The exact reason for failure is given under the heading Diagnostic information for administrators. Below we give some explanations of the common failures including the instructions how to resolve them.

1. 550-RPT-UNK: Recipient unknown

The email address that you are trying to contact does not exist. If the address is an Oxford address, this may be because:
  1. the person has left the University,
  2. the address you are using is no longer a valid address for the person you are trying to contact.

To find the email address of a member of the University go to University Contact Search.

2. 550 5.1.1 RESOLVER.ADR.ExRecipNotFound

If the offending email address is reported to be something like
then it is likely that your email client attempted to use a Nexus internal address of this recipient. This sometimes happens if you email them before their account was migrated to Nexus and your email client remembered their old internal address that is now no longer valid. To resolve this problem you must delete the address that is cached in your client.

Outlook 2003 and 2007
Outlook Web Access Premium (Internet Explorer)

The incorrect entry in your autocomplete list will be replaced with the newly selected address book entry.

In Outlook Web Access Light
In Entourage

If the format of the address does not match the above then another server refused to take delivery of your message. Scroll down through the message and look for any information returned by the remote email server that may indicate why this has occured.

3. #554 5.6.0 STOREDRV.Deliver; Corrupt message content

This error message indicates that the message sent was corrupt in some way.

The most common cause of this problem is that some (older) versions of Thunderbird or Firefox and their derivatives incorrectly send some attachments, which Nexus refuses to accept. The setting appears to be preserved in the profile folder and hence it may also happen even if you have the latest version of Thunderbird or Firefox.

Thunderbird or Firefox
The profile folder for Thunderbird is found in the following locations (replace the terms in capitals with locally valid terms):
The profile folder for Firefox can be found in the following locations (replace the terms in capitals with locally valid terms):