<blockquote> How can I ditch ALL references to the office365 and aol/verizon accounts </blockquote> If there is no mail you want to keep in those accounts, you can delete them in Thunderbird. Press Alt or F10 in case the menu bar is hidden. From the main menu bar: Tools - Account Settings Select the account to be deleted in the left pane. Select 'Remove Account' from the 'Account Action' drop-down menu at the bottom. Note, this removes the account(s) in Thunderbird. They still do exist on the email provider's server though. <blockquote> a new TB account </blockquote> There is no such thing as a TB account. See https://support.mozilla.org/en-US/kb/thunderbird-faq#w_what-is-my-thunderbird-email-address <blockquote> do the iphone email settings override the desktop email settings </blockquote> I'm not sure what that means. What are you trying to achieve in the first place?