Your email is set up and ready to go. You have POP and IMAP access -- I highly recommend IMAP -- and all the aliases you asked for in your signup form are working and forwarding to your account.
You only get a single account per user (maintaining Postfix is hard!), but you can have as many aliases as you want. Email me if you want more.
Postfix also understands the "+" hack for email addresses, so you can use something like "jacob+something@gypsyhosting.com" -- this is good for spam fighting.
You can filter mail through procmail; make a .procmailrc in your home directory.
http://webmail.gypsyhosting.com/ is an install of RoundCube webmail. All in all it's an amazing product -- by far the best webmail available -- but its PostgreSQL support is sketchy at best. It works, but every so often you'll get an error or two. I'll fix 'em as quickly as I can find 'em in that PHP-soup.