When an email arrives in your mailbox that looks suspicious and is not on your Allowed People or Companies lists, MailFrontier Desktop sends an Email Challenge to the sender. Once an accurate response to the Email Challenge is received, the original email is delivered to your inbox. Email Challenges are randomly selected questions that are very easy for real people to answer. You can decide when to send a challenge and even personalize the challenge.

Spam Messages
Most junk email is sent from invalid email addresses. Therefore, such junk email senders will find it impossible to answer the Email Challenge, because they will never receive it, and you will never see that junk email in your inbox.

Real Messages
If the sender is a real person, she/he simply replies to the Email Challenge to receive permission to communicate with you.