Posted 07 July 2012 - 03:25 AM
When you say "make a email service", are you referring to something like Gmail/Yahoo, a corporate/group project, or just a personal @yourdomain.com email? The below answer is to starting something like Gmail/Yahoo, but it should fit for the corporate scenario as well. Doing personal @yourdomain.com is alot easier, however.
With only 8mbps (assuming that's the uplink side), you would probably be best going with a VPS or dedicated server in a commercial datacenter. 8mbps is very low for a full-out "service", if you're going to be offering this to multiple people. Most datacenters you can get 100mb/s - 1gb/s for just a few bucks more a month. The only problem comes that you would need to either colo (put a server in their datacenter) or lease a server from them. By leasing you will also be able to have them install firewalls and other security features to help protect again DDoS attacks (as you mentioned above).
Having said that, what experience with web development do you have? Starting out a single server should work fine, but later on you will need multiple IPs and servers to send email since many places are blacklisting IPs due to how much mail they send per hour/day. You will also either need experience in or hire a developer to code custom webmail clients (or use one of the freely available ones - which you can not theme to your own products that well, but it is possible).
Copyright wise - you shouldn't run into too many things. Legal wise, however, you would need to make sure the service wasn't abused to send spam and record information such as IP addresses from the users in case any threatening/abusive email was sent from your server.