[Chris M]

Thanks for all the replies. Simbr's answer seems the most likely explanation - the mail servers my friends are sending from have been blocked by ntlworld because of their poor attitude to dealing with spam. It would be nice if Ntl had an area on their website where users can check which servers are currently blocked (looking at the Sorb site this seems to change from one week to the next)

Whilst I appreciate efforts to prevent spam it is frustrating that so many genuine emails are being blocked - at the moment it is reaching the level that I may have to change ISP although there seems no way of knowing whether any other service provider would be more efficient.

Thanks again,

Chris