Got an email problem to throw at you --

User tries to send email to that forwards email to, but it bounces back like so:

The following recipient(s) could not be reached: on 3/6/2006 9:34 AM

There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.

< #5.5.0 smtp;554 <>: Relay access denied>

Googling the 554 error, everything I've thus far read said it's a problem with the sender's SMTP settings. However, this user can send email to anyone else, just not this particular user.

I checked the settings on the server that handles email forwarding, and all that's configured as it should be -- is indeed configured to pass email along to