Email by itself (as a protocol) is far from perfect, but you can have other mechanisms to improve on top of it where it falls short (while some other things, like metadata retention, are deal breakers). You can still host your own email with almost all the bells and whistles offered by Google/Microsoft, so you have that going for you.
On the other hand, even if you have the greatest and most secure emailing server imaginable, you would still be communicating with others who don't use it, and you're relying on them having some strong security mechanisms as well. Therefore, it's important for Google/Microsoft to make these improvements on top of emails as well.
So, if we're talking about email as a protocol, not secure enough for 21st century.
If we're talking about email as an end product, then yes, it's secure enough (under the assumption that you're using some well known email hosting service).
Email by itself (as a protocol) is far from perfect, but you can have other mechanisms to improve on top of it where it falls short (while some other things, like metadata retention, are deal breakers). You can still host your own email with almost all the bells and whistles offered by Google/Microsoft, so you have that going for you.
On the other hand, even if you have the greatest and most secure emailing server imaginable, you would still be communicating with others who don't use it, and you're relying on them having some strong security mechanisms as well. Therefore, it's important for Google/Microsoft to make these improvements on top of emails as well.
So, if we're talking about email as a protocol, not secure enough for 21st century.
If we're talking about email as an end product, then yes, it's secure enough (under the assumption that you're using some well known email hosting service).