How to remove letters from trash back to Inbox?

the question is at the topic.

Go to trash, select the mail and move it to the inbox.

There is no “undelete” function in K-9.

Body, nope! there are only next buttons: delete, star, unread and select all.

Go to the Trash folder, longpress the email, 3-dot menu, Move (or Copy), in the next window select where to.