Mail using too much storage space.

See the articles https://support.apple.com/en-in/guide/mail/mail14059/13.0/mac/10.15

https://support.apple.com/en-in/guide/mail/mail14059/13.0/mac/10.15

https://support.apple.com/en-in/guide/mail/mail14103/13.0/mac/10.15

https://support.apple.com/en-in/guide/system-information/sysp4ee93ca4/mac

drclifford. wrote:

Mac Mail is using 224.11 GB storage. Erasing emails does not solve the problem. How to I free up storage and prevent it from happening again? I want all mail stored on the cloud.

If the email account in Mac mail is an iCloud account, it is synced between your Mac and iCloud.

There is no "On iCloud only" option.