Cannot get IMAP/SMTP account to accept credentials

eM using MX records for account setup. This is an old account; IMAP/SMTP.

I am using a spam protection service for which I enter THEIR 4 MX records.  When I click ‘fix’ I can see the list of a number of records flashing by before it fails.  I’ve changed passwords endlessly and nothing will go thru.  Could eM be mis-interpreting my MX records? 

I must have the spam protection - the account became a spammers dream a couple years ago and this service makes it useful.