550 5.1.1 unknown or illegal alias

[Carl]

I have a user trying to send to another user on the same network
through Outlook 2003.
When she sends email to the other user, the following error message is
returned-

The following recipient(s) could not be reached:


Zaira Lara on 4/12/2006 2:11 PM


550 5.1.1 unknown or illegal alias: (e-mail address removed)


Zaira Lara on 4/12/2006 2:11 PM


550 5.1.1 unknown or illegal alias: (e-mail address removed)


I've seen this error message posted elsewhere, but the posts were for
people receiving this message from an external source for mail they did

not send.


Anybody have any ideas?

 

[Guest]

The most common definition of this error is:
Another problem with the recipient address. Possibly the user was moved to
another server in Active Directory. Maybe an Outlook client replied to a
message while offline.
I understand that the user is sending within the organization. Is it
possible that the user has the recipient set as a contact rather than simply
using the GAL? Is she perhaps using an incorrect address as a result?
It's also possible she is choosing this person from the "names cache" or
nick list, it's also possible that she once typed in the address incorrectly
and is choosing that incorrect entry?

 

[Carl]

Well, they only have one server. Not sure about a message being
replied to while offline.
I had the sending user pick the recipient user's name from the GAL.
The address is correct.
I'm headed to the site now. I'll post more details when I return.