Hello - I've got a lovely new website with its relevant email addresses attached. I can always receive emails, and sometimes I can send 'em. Mostly though, I get the message 'Sending of message failed. This message could not be sent because connecting to SMTP server mail.xxx.org.uk failed. The server may be unavailable or is refusing SMTP connections. Please verify that your SMTP server setting is correct and try again, or else contact your network administrator' and I never change any of the settings in between being able to send things and not being able to send things.

Thunderbird is my email programme, and I'd rather not have to send my work email through my gmail account.

All suggestions welcome - cheers!

If it's an intermittent issue even when you have made no changes to the settings, the first thing that you should try is contacting the ISP. They may have had other reports of problems on that particular mail server and they might give you different settings so that you use a different mail server instead.