I’ve only ever seen the legal “right to be forgotten” concept applied to search engines and news publications. I think the closest to this was in Delhi high court where they ruled to have some social media “news” posts deleted. But that’s far different from having platforms erase things you’ve said and may regret. And then add yet another degree of separation for using a semi-private form of communication in email.

I am not speaking authoritatively so anyone who knows more than me jump right in.