[antiRepublicrat]

That's the only platform that software that met the specs we needed was available on

It's possible, but I've also seen a lot of specs written to get one specific application, not to the actual needs.

And I'm still waiting on the open source Exchange Killer app.

OS X Server does have enterprise-capable mail and calendaring functions integrated with the directory, and they're based on open standards so, unlike with Exchange, you're not locked-in. It's included for unlimited clients, as opposed to Microsoft, which charges tens of thousands of dollars to get unlimited clients from Exchange -- per server, of course.

[tacticalogic]

OS X Server does have enterprise-capable mail and calendaring functions integrated with the directory, and they're based on open standards so, unlike with Exchange, you're not locked-in. It's included for unlimited clients, as opposed to Microsoft, which charges tens of thousands of dollars to get unlimited clients from Exchange -- per server, of course.

What do they call this application? I'm guessing they're not keeping the users's mailbox in an LDAP directory.