Mark as Done moves the email to the Done column of your Later Board and marks it as such. It indicates that there's nothing more to do with this email, but it's still valuable enough for you to keep — it stays in your inbox, just tagged as handled.
Mark as Done moves the email to the Done column of your Later Board and marks it as such. It indicates that there's nothing more to do with this email, but it's still valuable enough for you to keep — it stays in your inbox, just tagged as handled.