I use a Mac with macOS 10.12.2 (Sierra) and have MS Office 2016 (and also 2011) installed. My usual browser has been Safari, but I want to be able to use Outlook occasionally, or as a backup. I have three email accounts: gmail, btinternet and icloud.

Using automatic account setting-up, the gmail account now works correctly.

The icloud one (as set up in Outlook) refuses to accept my password — which I have checked on other Apple sites that require a password to be correct as entered.

The btinternet one appears as a POP account, which it is not — it is an IMAP one — and also will not accept my username and password (both of which work on the bt website and therefore obviously correct).

Outlook 2016 and Outlook 2011 behave identically in this respect.

I should be most grateful for advice.