When you enable WhoisGuard service for a domain, it puts its address information to the public Whois instead of yours to protect you from potential spam and even identity theft. 

Your personal email address will be replaced with a unique WhoisGuard one (e.g., 35180ba032214a9387fe517f46b6037d.protect@whoisguard.com), and every email sent to this WhoisGuard email address will be forwarded to an email address of yours.  

To enhance online presence privacy, you also have an option to schedule the change of your WhoisGuard email address every few days. This should provide you with additional protection from spam as mail harvested from Whois becomes invalid in a few days.