Hi Noel,
thanks for the reply, I seem to have solved it by making my outgoing server require authentication, same as incoming. I can send again which is a relief. The error message was 530, requires authentication, although I had never had to do this before but I take my laptop away for work with me and I think for some reason using other wifi connections had muddled it.
Anyway, thank you for taking the time to reply.
RM