That's here that you will be able to protect your mailboxes. The screen is as below and very simple to complete

1. Enter the name of your server smtp: it is the server responsible for the sending your mails. The simplest solution consists to use the Server smtp of your active connection . If you want to manage a Wanadoo address while being connected by Free, it will  be necessary for you to enter in parameters of the account the POP server of Wanadoo (pop.wanadoo.fr) and server smtp of Free (smtp.free.fr). Please note that the address of server smtp does not always  start with smtp but sometimes with POP.
2. Enter the SMTP port number, usually 25
3. Enter the name of the POP account.
4. Enter the POP port number, usualy 110
5. Enter the name of the mailboxe that will be used to "challenge" the unknown senders.
6. Enter the storage delay (here 4 days). After this delay, people who have not respond to your challenge will be cleared from your quarantine list.
7. If someone tries to reach you more than this number without answering your challenge, you will be alerted by an administrative email.
8. That parameter throw in black list every people that have tried to contact you more than X time without responding to your challenge. That prevent you to go in a loop with a robot for example.
9. Your challenge. Choose something simple
10. Response that you accept.