In general... don't give out information that's not needed... and give out fake information when not needed, but required by stupid webforms.<p>So yeah, I'll give actual information to government, insurance, bank etc, but mostly bullshit (even name, DoB, etc) to (web)shops. Besides the address a shop doesn't need anything from me, so they usually get a throwaway e-mail, no phone-number or 0123456789 and only a postal-address if buying physical goods for delivery.<p>For mail-addresses where I need them later, always just customize them (like with gmail using youraccount+webshopname@gmail.com or with self-hosted using postfix's + or - address seperator).