If you host your own domain, you typically will have the option of a 'catch-all' email address alias. This means you can specify the email address that receives all email that doesn't match up to your pre-created email addresses. I've set my domain to forward them all to my 'secondary' email account and have started using this to try an monitor how my email address is ending up in SPAM mailing lists. For instance, when I need to provide a valid email address to a mailing list online, or to receive a trial license key for software, I use the name of the list or company itself in the username field of the email address. When I receive email to that address, there is no doubt of where it came from. If they turn around and sell that email address, there will be no doubt as to who sold it. This is useful for any instance where a valid email address is required. The local library. The dentist. That new car contest at your local mall. Let's start seeing how our email addresses really get passed around. For throwaway email addresses that just require a single exchange, check out Mailinator. When signing up for something where you need such an address, just specify <somename>@mailinator.com and submit. To go and retrieve the sent email just visit the Mailinator homepage, type in the email address you just used (no password or registration needed!) and it displays any received email. No spam worries.