The choice between hosting e-mail in-house or outsourcing it to a third party is ultimately one of responsibility and control. Can you handle the responsibility of keeping your service up and running? If not, are you willing to sacrifice the control you would otherwise have over it? E-mail hosting providers such as Webmail, Simplicato, and Rackspace offer premium e-mail services on custom platforms. For a fee they’ll configure your e-mail, provide you with a domain name, and give you a large number of accounts. They’ll also provide 24-hour maintenance and redundant backup.
In-house hosting requires that you set up and mange your own e-mail server, which gives you more flexibility and control. And because you aren’t paying for storage you gain a little flexibility: You can make e-mail accounts as large as you want, add accounts easily, or host multiple domains.
For more on e-mail hosting, be sure to read E-mail Hosting: In-House Servers vs. Third-Party Providers.