it is exceedingly difficult to find a setting that does not exist. There is no successful method of "Pausing and account" if you account is IMAP. Usually if the account is not available on the server at some point all the mail held in Thunderbird will be deleted. A pop account you just disable the checking of mail in account settings, but that does not work effectively for IMAP account and that is what almost everyone has. The idea has already been submitted to the ideas forum https://connect.mozilla.org/t5/ideas/ability-to-deactivate-email-accounts-in-thunderbird-temporarily/idi-p/81979 and https://connect.mozilla.org/t5/ideas/allow-thunderbird-user-to-enable-disable-an-account-temporarily/idi-p/29194 This is not the place to discuss a wishlist.