If you are trying to send an email using the tesco.net server, but using a different ISP to connect to the internet, you can sometimes get this error. This is to stop people using the tesco server (or any other ISP mail server) to send spam emails.
Actually, if he's using a different ISP to connect to the internet and trying to send email through the tesco.net email server, chances are, he'll get something to the effect of a 550 Error (I think that's the number), but will spit back a message that says "Relaying not permitted"... Sounds to me like either the mail server is on the fritz and can't keep a TCP/IP connection open for an extended period of time... or could be some other random connection problem... Definitely weird, though, and I can't say I've seen that particular error msg before
EP, glad to see you come back and tidy up...did want to ask a one day favor, I want to enhance my resume , was hoping you could make me administrator for a day, if so, take me right off since I won't be here to do anything, and don't know the slightest about the board, but it would be nice putting "served administrator osnn", if can do, THANKS