Sometimes senders might receive the following non-delivery report:

A problem occurred during the delivery of this message. Please try to resend the message later. If the problem continues, contact your helpdesk.

Bounce

The Diagnostic information for administrators section contains the following error:

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

Diagnostic info

This bounce back message is generated in the following scenarios:

  1. User A has forwarding set up to a Distribution List B. User A is a member of this Distribution List B.

To resolve the issue please use one of these options:

  • Remove the forwarding from this User to this Distribution List. Read the Knowledge Base article on How To Forward Messages From Your Exchange Mailbox for more information.
  • Verify if the the User needs to be added as a member to this Distribution List. Read the Knowledge Base article on How Do I Manage Distribution Lists In Exchange for more information.
  • Enable option Save copies of forwarded emails in the forwarding configuration for each User. Read the Knowledge Base article on How To Forward Messages From Your Exchange Mailbox for more information. 
  1. User A has forwarding set up to User B. User B has forwarding set up to User A.

To resolve the issue please use one of these options:

  • Remove forwarding from one of the Users. 
  • Enable option Save copies of forwarded emails in the forwarding configurations for each User 
  1. User user@yourdomain.com has alias user@yourdomain1.com and has forwarding set up to this alias user@yourdomain1.com (Alias was initially added as Company Contact to setup forwarding). 

To resolve the issue please use one of these options:

  • Check the current aliases for the User.
  • Remove forwarding from this User to the email address that is set up as an alias.

Note: if you are using this scenario for migration purposes or you have different exchange servers, please remove forwarding to alias and use Split domain option.