This presumably means that there is a SMTP server error. If I log into webmail password information is correct and the Mail alert disappears for a while.
Two questions that perhaps the forum can help with:
why does this happen - BT SMTP server seems to dislike connection when not on a BT Broadband service - obviously not possible when abroad
how can I avoid this - I remember reading about ignoring the BT SMTP server and using an alternative SMTP server (such as a Gmail account) - if I do this email sent from my account does not appear to come from my BT email address