And you somehow trust Slack as a "secure alternative"?

Where did I imply that? There are tons of options for business chat. My point was only that email isn't even in the running.

The security model for internal email on a corporate email server is pretty similar to a corporate slack instance.

I've never seen any email system used securely. Even smart people will send sensitive info to a personal address instead of corporate, for example. Email wasn't purpose-built for controlled internal comms.

Part of this is a UI problem, but it's still a problem.

I didn't say Slack is the answer, either. Just that email isn't a serious competitor to Slack.

If you want secure emails use GPG. Unlike slack, GPG is both open-source and offers government-level security. I don't think slack is more secure than GPG.

Companies are generally at more risk from failure to produce message content in a lawsuit, regulatory action, HR investigation, etc. than from eavesdropping. "Secure" in a corporate setting means subject to IT's surveillance, filtering, and archiving. If anything, security's job is to make sure employees aren't using things like PGP, personal webmail, Facebook, etc. to evade corporate retention policies.

Maybe mysterious quasi-state actors will steal your secrets and outcompete you decades from now, but they could probably do that anyway. The SEC will certainly fuck you up right now if you can't demonstrate adequate controls on regulated employees' communications.

I'm talking about personal e-mail. Still businesses can easily enforce retention policies with PGP by using a master key.

If that were viable people would already be doing it. It's not, and so very few people are. I wish this weren't the case but it is.

And how does that work for your average person using outlook / google for email?

Then build on top of email, instead of developing yet another 'secure' proprietary system.