For all you people, supporting IMAP mail on Outlook. Beware the New Outlook app. Not only does it not quite support all IMAP accounts. It sends the login details and stores them ON MICROSOFT'S servers.
Some details here https://answers.microsoft.com/en-us/officeinsider/forum/all/imap-support-for-new-outlook-for-windows/469fd2ef-9d44-42f3-800c-dda6d69e3c9c
and Yes, I personally use Thunderbird, I suspect ill be setting this up for people quite a lot soon.