we actually have something like this, but it's a too-specialized system, so it's not possible to send "mail" to people unless you're a big enough company to reg

we actually have something like this, but it's a too-specialized system, so it's not possible to send "mail" to people unless you're a big enough company to register for that privilege, and users can't reply via the system, so it's a receive-only solution that's also incompatible with standard technologies.