A couple of ideas: '''1:''' * Create suitable folder to receive tagged emails * Use 'Quick Filter Bar' Tag icon to 'show only messages with tags on them' * Highlight all emails - select first email then 'Ctrl + A' * Right click on highlighted emails > 'Move to' and choose folder. * Clear the 'show only messages with tags on them' by clicking on the icon to show all remaining emails that have no Tags. * Highlight remaining emails or subset and click on 'Delete' '''2:''' If all your 'tagged' emails were also marked with a star, then you could set a retention policy on the folder. * Use 'Quick Filter Bar' Tag icon to 'show only messages with tags on them' * Highlight all emails - select first email then 'Ctrl + A' * Right click on highlighted emails > Mark > Add star * Clear the 'show only messages with tags on them' by clicking on the icon to show all remaining emails that have no Tags. Note using the following setting on the selected folder will delete from Thunderbird AND off the server once you click on 'OK'. So be sure this is the action you want. * Right click on folder and select 'Properties' * Select 'Retention Policy' tab * Uncheck 'Use my account settings' to offer more choices. * Select 'Delete messages more than eg: 7 days' * Select: 'Always keep starred messages'. * click on 'OK' As all tagged emails are now starred they should not be deleted. If in doubt as you may like to test this action - suggest you create a copy of all tagged emails and put them in eg: 'Local Folders' or create a backup of entire profile if you have not one recently. After using the 'Properties' > 'Retention Policy' option on folder, you could reset to use account settings or leave as is. If left to auto delete, then it might be a useful precaution to use a filter to add a star by default to all new mail. Removing the star upon reading if deciding to discard and leaving star but adding tag as required.

Thanks Toad Hall