Some (but not all) of my users are getting the following NDR when trying to email a user:
The recipient's e-mail address was not found in the recipient's e-mail system. Microsoft Exchange will not try to redeliver this message for you. Please check the e-mail address and try resending this message, or provide the following diagnostic text to your system administrator.
IMCEAEX-_O=EXCHANGE_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+28FYDIBOHF23SPDLT+29_CN=RECIPIENTS_CN=Fred+2EJones@domain.com#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##
Fred Jones (email@example.com) is a valid address though which is strange. And, like I said, some users can email him fine.
Can anyone shed any light on this? Running Exchange 2007/ Outlook.