Make sure Mailer is open on the desktop and its Message Header List is visible.
Open the mailbox to which you want to move the message and make sure you can see the Message Header List.
Select the message to be moved.
Drag the message and drop it onto the appropriate mailbox Message Header List.
The message is moved to the end of the target mailbox.
You can also drag and drop a message to the file icon of the target mailbox in File Manager. With this method, Mailer places a copy of the message in the target mailbox instead of moving it.