I am setting up a multisite network and wondered what you

I am setting up a multisite network and wondered what you guys normally do about email?

I don’t want to use Google Apps in this case because it would be too expensive.

I want each site to be able to have emails eg: me@site1.com – however site1.com will be mapped to site1.mysite.com – and won’t have a cpanel…so how do i go about setting up email for my clients?

Thanks