The following non-delivery report:

A problem occurred during the delivery of this message to this email address. Try sending this message again. If the problem continues, please contact your helpdesk.
A problem occurred

means that the recipient mail system did not accept the message either beacuse of a temporary issue on any party's end or because the recipient email address was not found in the recipient system.

The Diagnostic information for administrators section may contain the following errors:

#5.0.0 smtp; 500 Invalid recipient (#5.1.1)

Invalid recipient

#5.0.0 smtp; 500 No such user here

No such user here

Both these errors are usually generated in cases of external delivery (from Smarsh Hosted Services mailbox to an external recipient). They indicate that either the spelling is wrong or the recipient mailbox no longer exist. You can check if that is the case by:

#4.0.0 smtp; ESMTP not accepting connections

ESMTP not accepting connecitonsThe error is usually generated when the sender's IP address is listed in a Real-time Blackhole List. While it is the sender's responsibility to ensure their IP address doesn't get listed in a Real-time Blackhole List, you can contact Support for IP address removal evaluation.

If the IP address, however, is listed on other public Real-time Blackhole List, contact the sender so that they could request delisting.

#554 5.7.1 Service unavailable; Client host blocked




The error is usually generated when the sender's IP address is listed on invaluementSIP or Spamhaus. To delist the IP address:

Note: since Smarsh Hosted Services is not the owner of the sender's IP address, we can only work with our spam-filtering vendors and not any other RBLs.

#550 5.4.6 RESOLVER.FWD.Loop; there is a forwarding loop configured in the directory

Read the Knowledge Base article on There Is A Forwarding Loop Configured In The Directory Bounce Back for more information.