This test might perk your interest:
-While they use several machines to do the testing, the goal is to test the load an a zimbra mailstore running on one, dual-core dual-cpu machine (connected to a SAN backend).
=final result 50,000 active users/hr (200k provisioned users)each with 8 recieves, 8 reads, and 8 sends... served at once by one mailserver, (also using an mta, one external ldap, and one SAN)
and that was back in 2006 with zcs v3 I believe
Service Provider Benchmark
Not that comcast will ever release it...but I would personally love to see statistics on their setup; how many servers (and of what type), mail traffic stats etc. But I'll wager on that never happening-as I'm sure they don't want to run the chance of giving away info to competitors
