550 5.1.1 ... User Unknown but user is known

[remain]

This one company repeated at random times gets this error when trying to email a few different people in my company:

===== Original Message from MAILER-DAEMON@mail.theirdomain.com at 4/28/04 12:48 pm
>An error occurred sending a message to:
>ouruser@ourdomain.com
>
>Relay host reported error: (ourdomain.com)
>550 5.1.1 <ouruser@ourdomain.com>... User unknown
>
>
>Original Message Follows:
>=========================
>
>Reporting-MTA: dns; mail.theirdomain.com
>
>Remote-MTA: dns; ourdomain.com
>Final-Recipient: rfc822;ouruser@ourdomain.com
>Action: failed
>Status: 5.0.0
>Last-Attempt-Date: Wed, 28 Apr 2004 12:48:34 -0400

our user is definitely a user with no problems receiving mail from anyoneone else, the accounts that their user CAN send to in our domain are no different in configuration than the ones he CAN'T send to (aside from the obvious).

This has been happening on and off for weeks, and we are concerned that other people may have been getting this error and haven't been notifying us or haven't been able to.

thanks in advance

 

[AGig]

Have you received help with the unknown user problem? We are experiencing the same problem trying to send email to this particular address. We can receive mail from them but mail going out to them gets kicked back with the unknown user error? If you have resolved this it would be much appreciated if you could tell us how you did it.

Thanks

 

[TawneeS]

Have you guys figured anything out? I'm having the same problem any info is appreciated