On Thursday, 19 October 2017 18:27:41 BST Neil Bothwick wrote:
> On Thu, 19 Oct 2017 10:56:18 +0100, Peter Humphrey wrote:
> > Yes, I have all those set right. The first thing I did was to go
> > through all the Configuration dialogues and put values in.
> 
> Screenshots please!

Could it be your mail provider is using OAUTH2 like Gmail does?  If so you 
will need to tweak Google's (your ISP's) security settings to allow non-OAuth 
authentication mechanisms, or look into obtaining an OAuth token and use this 
instead of your normal login passwd.

I'm somewhat thin on the details, but if this is the cause of your problem the 
interwebs should provide steps to help with the particulars.

-- 
Regards,
Mick