There is quite a number of third-party apps out there.
#Manage space on mac how to
How to delete Mail app on Mac using third-party apps The former will save you time and stress. You can use a third-party app, or do it manually. The mail app on Mac is a system application that makes it near impossible to be deleted for a non-tech-savvy user. Underneath, you’ll find out how much space attachments are occupying, select and delete all attachments you no longer need. Click the Storage tab and then select Manage -> click on Mail in the left-hand sidebar. Click on the Apple menu and select About this Mac.
These attachments range from sent documents and other files to signatures from subscribed company newsletters. Mail storage is consumed by various attachments that come with your emails.