Interested in improving your mail system, and refreshing your aging software and hardware. (Man, if that doesn't sound like a marketing intro, I don't know what is.)
Read about how Telstra (with a 300,000-strong ISP customer base) consolidated onto Messaging Server, T1000/T2000 servers, and Solaris 10 OS:
Sun completes TelstraClear mail upgrade
TelstraClear completes successful email systems consolidation
As I understand it, the Sun Groupware Migration Toolkit played a large part in this upgrade. You can read more about SGMT here: