The idea behind footbag.org's e-mail alias feature is that your alias (or member name) at footbag.org can be your "e-mail address for life". Basically, while many of us change jobs, change ISPs, and generally try out new services from time to time, we all share one passion that will (hopefully) stay with us for our lives -- footbag. So, instead of having to send out a huge e-mail to everyone you know, every time you change ISPs or jobs, you can go through that process one final time -- by telling everyone your permanent address is now your footbag.org address. Then -- this is the really important part -- you must make sure you keep your member profile on footbag.org up to date! (Because, we don't store mail for you -- we only filter it and then send it to your real mail box address.)
So, while you may change jobs, ISPs, or service providers for e-mail from time to time -- which is where you go to retrieve your mail and/or to send outgoing mail -- your friends and colleagues don't need to know that! You just give them your "permanent" @footbag.org address, and as long as you keep your profile up to date, your mail will always land in your real mailbox. And since it went through footbag.org's spam filter, you can rest assured it'll be "cleansed" of any unwanted spam!
There's one hitch: some mail programs make it hard (or impossible) to hide your (otherwise private, somewhat temporary) mailbox address from your correspondents. For example, if you use Hotmail, and someone e-mails your @footbag.org address, it will end up in your Hotmail mailbox. When you hit "reply" in Hotmail, the reply will appear to come From: your hotmail address (not your footbag.org address). This is unfortunate. Some services allow you to change the From: address (most desktop mail programs do) but not all of them. If you can't figure out how to change your From: address in your outgoing e-mail, you should instead revert to the next-best alternative -- setting up a "Reply-To:" header. I think every mail system allows you to do this. It's not as good, but it's close -- it says that "good" mailers should send the reply to the Reply-To: address instead of sending to the "From:" address, when the receiver hits "reply". It's a compromise, but it's better than nothing.
Ask a friend to help you if this is all gobbledy-gook to you. You can change your e-mail address in your footbag.org profile by going to http://www.footbag.org/members/editprofile. (Note: you should make sure your private e-mail stays private, by making sure you configure your account to only show your @footbag.org address in your profile. Please be sure you check the "keep me informed" box, because this is the only way we can tell you about this type of service and changes to it!)