SMTP Communication and unknown user error

[bradhiggins]

Hey all,

I have one client, who, when connected to exchange server keeps getting a NDR when sending to 1 particular e-mail address.

The error is :

<to_emailaddress@thierplace.com> on 21/04/2004 1:28 PM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<myserver.com.au #5.5.0 smtp;573 client_email@myorganisation.com.au unknown user account>

I can send to this email address from another exchange account but not from the problem account.The client can receive from the to_emailaddress@thierplace.com

Any help would be gratefully appreciated.

Cheers

Brad

 

[xmsre]

My guess would be that the recipient has blocked the sender.

5.5.0 simply means that it's a permanent failure - other or undefind status. This error code is coming from the distant end.