550 mail error

I get the following error when trying to send a mail:

From: Mail Administrator <Postmaster@ntlworld.com>
> Date: Tue Dec 9, 2003 11:00:08 pm Europe/London
> To: ***.***@ntlworld.com
> Subject: Mail System Error - Returned Mail
> Reply-To: Mail Administrator <Postmaster@ntlworld.com>
>
> This Message was undeliverable due to the following reason:
>
> Each of the following recipients was rejected by a remote mail server.
> The reasons given by the server are included to help you determine why
> each recipient was rejected.
>
> Recipient: <***.***@btopenworld.com>
> Reason: Unknown local part ***.*** in
> <***.***@btopenworld.com>
>
>
> Please reply to Postmaster@ntlworld.com
> if you feel this message to be in error.
> Reporting-MTA: dns; mta6-win.server.ntlworld.com
> Arrival-Date: Tue, 9 Dec 2003 14:47:14 +0000
> Received-From-MTA: dns; ntlworld.com (81.96.96.253)
>
> Final-Recipient: RFC822; <***.***@btopenworld.com>
> Action: failed
> Status: 5.1.1
> Remote-MTA: dns; moongate.btinternet.com (194.73.**.***)
> Diagnostic-Code: smtp; 550 Unknown local part ***.*** in
> <***.***@btopenworld.com>

Anyone know what's going on? Mails to the ***.***@btopenworld.com address do not arrive.

Is this a problem on the ntlworld or btopenworld side.

If more info is needed, please let me know.

Thanks,

Spete

 

That could be the problem but only if it's part of a bad email address.

My work address is newt.vail@*********.com and it works fine.