Regular failure to connect to btinternet email

My friend’s emclient keeps telling her that her settings are wrong but then later connects.  It happens virtually everyday, not over Christmas, at about 8am until late at night.  She’s trying to run a small charity and it’s causing major problems.  

One thing you can try is in the account settings, on the Diagnostics tab, click Diagnose and then the Fix option if it is presented.

Which email provider is she using?

Oops, sorry, you already said btinternet.

Check that the following settings are there in the account settings:

Port: 993 (IMAP) 995 (POP3) 465 (SMTP)
Security policy: Use SSL/TLS on special port (legacy)