.

To EDIT settings and passwords on existing Mail Accounts:

(Make sure you are using the Incoming and Outgoing server names: mail.montanasky.net

this page has other names in their examples! )

 

Main Link 

https://help.dreamhost.com/hc/en-us/articles/222597488-Mac-Mail-How-to-make-changes-to-an-existing-Mail-account