#1. Your personal email. You never post it publicly anywhere, you just give it to friends. The address never changes.
#2. Your legitimate corporate email. You use this to register with your bank, etc. Since they're untrustable spamming whores, this email address is not safe. You still probably check it every day, but when it becomes tainted you just drop it and get a new one.
#3. Your temp/junk email. This is for use when registering at web sites, etc. basically all the very unsafe uses where you just need an email address and don't actually ever want email from them. You don't even check this in your normal email client.