How to Delete Mail From a Mozilla Thunderbirdby Jason Artman
Thunderbird is the name of a free email program distributed by Mozilla, the maker of the Firefox web browser. If you have been using Thunderbird, you might have noticed the growing size of your inbox and wondered how you can reduce the clutter and remove messages you don't want. You can delete unneeded mail from Mozilla Thunderbird to conserve hard drive space and ensure that the program performs well.
Click on the message you would like to delete. To select multiple messages, hold the "Ctrl" key while clicking on each one. You can also select several messages that are grouped together by clicking the first, then holding the "Shift" key while clicking the last.
Right-click on one of the highlighted messages and click "Delete Selected Messages." Note that this sends the highlighted messages to the Trash folder but does not delete them permanently. You can still remove messages from the Trash folder at any time, and they still take up space on the hard drive.
Click the "File" menu at the top of the screen, then click "Empty Trash" to delete the messages in the Trash folder.
Click "Yes" to confirm that you wish to delete the items in the Trash folder permanently. The messages are now gone.