Honestly - don’t. Not unless you intend to be their 24/7 tech support…

Very cool. I have a dragon egg one - been working very well for quite a few years now.

True, but it presumably would still require the user to open them.

But, I was mostly worried that just having the server installed would be enough.

It’s only if you view a specifically crafted email in the web client… still worth upgrading of course.