To select all emails in a folder:

• click on folder to see emails
• press 'Ctrl' + 'A' keys and all emails should get highlighted.

A list of 'conversations will appear in the lower Message Pane

• click on 'Delete'

To completely remove all hidden marked as deleted emails and release space in the folder:

• right click on folder and select: 'Compact'

If you would like old emails in a particular folder to be deleted on a regular basis, you can set up a 'retention policy' on a folder. Please note this will delete messages in Thunderbird and originals on remote server.

• Right click on folder and select 'Properties'
• select 'Retention Policy' tab
• uncheck 'Use my account settings'
• choose from the options listed
• eg: select : 'Delete messages more than xx days old.'
• click on 'OK'

Thanks for your reply, I have just moved over to Thunderbird and previously just right clicked a folder which then gave me the option to delete all. why is this not available in Thunderbird? I am a great believer in the KISS formula. Again thanks

It is possible that no one has requested it.

However, it is also possible to accidentally delete the entire contents of a folder accidentally. This method is not so quick, but it does help prevent such mistakes.

The 'Junk' and 'Deleted' (also known as Trash) folders do have a right click 'Empty Junk/Deleted' options.