What's to maintaining an e-mail system?

See my post for hosting a dedicated server. For the email system, it is most unlikely that hosting company will dedicate another server. What they will do is:

1. You'll need to buy a domain name
2. Incorporate that domain in their email system so that your domain can send/receive emails
3. They will allocate some amount of space for your emails. You can influence this factor with $.

If they say they will dedicate a server just to host your emails, I will double-check. Adding an additional email server to the network requires a lot of extra work: firewall, additional IP, backup email system, anti-virus, spam filters, etc.

You'll be paying the hosting company.