Kasmail Antispam aliases are a great idea:
Most websites require you to register by providing them your email address before you can access their services. Usually this is not a problem, but some sites will sell your personal information, including your email address to other companies for commercial sollicitation. This is when you start receiving SPAM.
Once your email address has been given away, you can't control who has access to it and what it may be used for. Therefore, it is a good idea to give it away only to your contacts, and to use a disposable address to register with various websites you visit.
A disposable email is an address that KasMail creates for you for a set period of time, ranging from a few days to a few years. All the messages sent to the disposable address are automatically forwarded to your regular email address. When you decide that you don't want to use the disposable address anymore, for example if you are receiving too much spam, just make it expire.
Disposable emails are really temporary aliases, and you can have as many as 25 disposable addresses at a given time.