Two possibilities he

1. You're not connected to the internet via 1and1.co.uk (ISP) when you're
sending; or...

2. Your account isn't configured correctly in OE. Check
with your ISP.
--
~Robear Dyer (PA Bear)
MS MVP-IE, Mail, Security, Windows Desktop Experience - since 2002
AumHa VSOP & Admin http://aumha.net
DTS-L http://dts-l.net/

Marc wrote:
Hi, wonder if anyone can help me sort this one out...?;

I got the following message when trying to send an email from outlook
express;

The message could not be sent because one of the recipients was rejected
by
the server. The rejected e-mail address was (removed for privacy, it
doesn't
matter what email address i try to send to, same message comes up).
Subject
'Read: Item number: 150305184567_proof copy enclosed', Account:
'imap.1and1.co.uk', Server: 'auth.smtp.1and1.co.uk', Protocol: SMTP,
Server
Response: '550 must be authenticated', Port: 25, Secure(SSL): No, Server
Error: 550, Error Number: 0x800CCC79


thanks for any help

Marc