You can use the buttons in the mail reader to navigate through your mail messages.
Click on Next to move to the next mail message in the file. Messages which have been marked as deleted are skipped.
Click on Previous to move to the previous message in the file. Messages which have been marked as deleted are skipped.
Click on Delete to mark the current message for deletion.
Click on Undelete to remove the deletion mark on the current message. This allows you to cancel any delete operation before you save the RMAIL file back to disk.