Ask HN: Managed corporate e-mail services

Google Apps is highly recommended but at $5/user/month it can get pricey. I'm interesting in providing inboxes to affiliates currently in the 300-400 range. I have found other services [1], [2], which are cheaper but it's difficult to choose the perfect service. I'd rather not host it, so what does everyone else use? [1] http://www.rackspace.com/email-hosting/webmail/ [2] http://www.zoho.com/mail/