Using the New Outlook for Mac features in business environments
When you change hosting the server name is going to be under a new name. I have to remove the email from the Outlook on Mac than add an email again it has to be directly with IMAP (omit ICloud). Please note IMAP is for those who can access the same email on many devices. Note the last part from below I have to change the password to new one first than insert, all old emails was recovered itself.
Tools>Minus>Sign Out On This Device>Plus>Add an Account>insert your email address>Continue>Sync directly with IMAP>Password