限制送信方以阻擋廣告信的郵件控管機制

Abstract

廣告信的問題近幾年來顯得越來越嚴重。由於電子郵件信箱的高暴露頻率，使用者每天都必須收下平均百封以上的廣告信件。不幸地，一旦某個電子郵件信箱被列入寄送廣告信的名單中，從此便不會被刪去，這使得廣告信的問題只會越來越嚴重，不會有減緩的一天。 為了解決這個問題，我們提出了一套和郵件伺服器結合、藉由限制送信方身分以阻擋廣告信的郵件控管機制。這個機制會要求第一次送信進來的通信者註冊，一旦對方註冊，使用者便能決定是否要讓對方註冊，若同意的話，對方便會拿到一個只有他能用的電子郵件位址，從此，若該通信者要寄信給這個使用者，他便需要寄信到這個特殊的電子郵件位址。這套郵件控管機制不僅能抵擋所有假冒或捏造送件者的廣告信，也能抵擋使用者不願通信的人。更重要的是，使用者甚至不需要親自記得對方給予的特殊郵件位址，一樣能像往常一般寄信或收信。最後，我們也實作了一個系統原型來測試，看看搭配了這套郵件控管系統的郵件伺服器改變後的效率，結果是令人滿意的。

Due to the unwitting exposure of email addresses to the Internet, almost every user will be forced to receive a large amount of spam everyday. Once an email address is found in the spammers’ list, unfortunately, it will never be removed from the list. Besides, spam could even be regarded as a denial of service attack against the whole Internet. Therefore, for fighting spam, we propose a scheme - Mail Access Control System (MACS), a system that uses a registry mechanism to block illegal emails or spam. Besides, in the MACS, there is a cooperative mechanism called Specific Sender Addresses (SSA) which are email addresses only given to the correspondents a user wants to communicate with and only allowed to be used by these specific correspondents. The length of SSA will be longer than the original one, so the transparency achieved by keeping correspondents’ SSA for users will be another important feature in the MACS. We will analyze the effectiveness of our scheme and evaluate the MACS by comparing the processing cost with the original mail server.