False 'Undeliverable' Message Going Out

[Mictain]

Afternoon all,

Whenever one of our customers sends an e-mail to our sales guy, the message gets delivered but the customer gets an 'undeliverable' message returned to them - "the recipient name is not recognised".

I have checked the sales guy's mailbox properties and it all looks fine to me.

Any ideas on why this is happening, please? At least the messages are getting through to us, which is good, but the message the sender gets isn't!

Many thanks,

Neil.

 

[franklin97355]

Where is the message being delivered from? Which Email server are you using?

 

[Mictain]

External customer across the pond (?) Or are you talking domain?
We're using Exchange 5.5 on an NT4 box atm.