The swipe feature could be extended by an "auto swipe" setting where one would set a default swipe action (for a sender's email address) and boxer would execute this swipe automatically in the future.
This is a fucntionality I found very useful in the "Mailbox" app. The user would execute a swipe action but hold the swipe button and not release it. The app would then come up with a list of mailboxes and the user would choose the default mailbox for the sender's email address. There should be an option whether an auto swiped email shall be marked as read or not. When it stays unread the user will always see which mailboxes have new auto swiped emails.