I've been on the atmail.com web site and they do a pretty good job of selling their services to companies.
The basic message is we'll handle and support your email services for a lower cost than hosting them yourself. That's a decent message, and probably correct because Atmail have got economies of scale. So porting the hosting of TPG email services would probably save TPG money without costing them customers, IF they continued to "subsidize" TPG's customers email services on TMC/Atmail.
Otherwise TPG will lose customers, maybe many customers.
