A method for blocking and / or filtering
electronic mail. Selected senders are provided with a valid passcode associated with an e-
mail address. When an e-mail is received at a mail
server node, a field in a header of the e-mail is checked for a valid passcode associated with the destination e-
mail address. If a valid passcode is detected, the e-mail is automatically sent to a
receiver at the e-
mail address. If an incorrect passcode is detected, the e-mail is automatically deleted at the
server node and does not reach the
receiver. If there is no passcode in the e-mail header, the e-mail is held temporarily, until the
receiver approves to receive the e-mail. If the receiver rejects the e-mail, the e-mail is deleted. The present invention includes an additional capability for the senders of e-mails to request a passcode associated with a specific e-mail address in a lookup
directory, before sending an e-mail to that address. Furthermore, the present invention enables firewall servers to block incoming e-mails only if they are received from the public Internet, thereby allowing all internal e-mails to reach the receiver without having to include valid passcodes.