Re: beginning of the end or the end of the beginning?
Seeing as those are both by miles the market leaders in their fields, the answer would undoubtedly be very few extra ones on Linux...And why would you want to - all those extra Linux security patches to integration test - not fun.
Ah, the MS shills are fast to react. As ACs yet again.
I'll give you a point: Exchange doesn't make much sense in Linux as it depends on Active Directory, MS's take on LDAPv3 and Kerberos5. But there are quite a bit of systems that can do what Exchange/Outlook does and they only require an LDAP server. And they're pretty secure as it is. On security patches, no platform is free from that. Especially Windows.