A method and system for sharing trusted contact information between trusted, known and unknown parties, without revealing the contact information itself, thus protecting the party defined in the contact from possible unsolicited messages known as “Spam”. Addresses of trusted senders are encrypted using a one-way encryption and stored in a whitelist repository that can be shared by different users. When a message is received, its senders address is extracted, encrypted using the same encryption method, and compared if it is found in the whitelist repository.