| 摘要 |
Systems and methods of filtering received messages to discard unsolicited messages using silverlist filters and combinations of silverlist filters and other types of filters are disclosed. In many embodiments, an appliance remote from a mail server is used to filter messages using at least a silverlist filter prior to forwarding messages to the mail server. In a number of embodiments, a mail server applies a filtering process that includes a silverlist filter and a challenge response filter. One embodiment of the method of the invention includes receiving a message envelope sent from a sender IP address, where the message envelope includes a sender address and at least one recipient address, determining the reputation of the sender IP address, allowing the message when the sender has a reputable sender IP address, irrespective of the sender and recipient addresses, and performing a test when the sender IP address has unknown reputation. In addition, the test includes issuing a temporary failure to the sender, detecting as a retry a message envelope received within a predetermined time period, where the sender and recipient addresses of the original message envelope and the received message envelope correspond, and allowing the retry message.
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