I would suggest a (paid) gmail account. You can access it using IMAP:
https://support.google.com/mail/answer/78892?hl=en
It's inexpensive (I think I pay $6 a month). No ads, built-in spam and
virus, awesome webmail intereface (if you ever need it), lots of
storage.
FYI: Microsoft and Google are phasing out Basic Authentication (username + password) for Modern Authentication (OAuth2). That might require some changes on your end.
