To delete a message, select it and press the Delete key, or click the Delete button in the toolbar, or press CtrlD, or right-click the message and click Delete.

When you press Delete or click the Trash folder, your mail is not actually deleted, but is marked for deletion. You can see all message marked for deletion in the Trash folder. To show deleted messages, click ViewShow Deleted Messages. You can view the messages striken off for later deletion.

To permanently erase all the deleted messages in a folder, click FolderExpunge or press CtrlE.

You can undelete a message that has been deleted but not expunged yet. To undelete a message, select the message, click EditUndelete message. Note that ViewShow Deleted Messages must be enabled for this.

If you have marked a message for deletion, undeleting it unmarks it, and the message is not shown anymore in the Trash folder.