Electrical computers and digital processing systems: multicomput – Computer conferencing – Demand based messaging
Reexamination Certificate
2000-03-10
2004-02-10
Maung, Zarni (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer conferencing
Demand based messaging
C709S203000, C709S207000
Reexamination Certificate
active
06691156
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to information delivery in a computer network. More particularly, the invention relates to techniques for restricting delivery of unsolicited e-mail, commonly known as “spam.”
2. Description of the Related Art
E-mail has become the communication method of choice throughout the business world as well as for the general public. In a typical enterprise environment, a mail server (such as UNIX SendMail) has a local mail delivery agent or client (typically . . . /bin/mail on UNIX systems) that stores an incoming e-mail on a local file system and delivers it to an end user via POP, IMAP or a command line program. Such agents typically provide the basic functionality of logging in an e-mail message and copying that message to a client machine's mail spool. Internet-based client-server messaging systems include, for example, Lotus Notes, which provides e-mail, calendaring, group scheduling, Web access and information management, integrated in an easy-to-use and customizable environment.
The rapid increase in the number of users of the Internet has made e-mail an attractive advertising medium. Unfortunately, however, e-mail is now frequently used as the medium for widespread marketing broadcasts of messages to large number of e-mail addresses. Large service providers and corporations are particularly susceptible to this practice, which is commonly known as spamming.
The desire to reduce spam has led to both regulatory and technical solutions. Several states have passed legislation that ban the practice of sending spam e-mail and impose criminal sanctions for violations. A summary of these regulations is available at the following URL: http://www.sork.com/spamlaws/state/summary.html#ok. Technical solutions include a number of techniques. The most common one is to filter unsolicited e-mail by blocking e-mails from particular e-mail addresses that originate such messages. This approach, however, is vulnerable to rapid changes in the source of the unsolicited e-mail, which is relatively easy because most spam is generated by automated means. Such approaches also typically require the set up and maintenance of a complex filtering mechanism.
Some e-mail clients, e.g., Eudora Pro, allow the end user to set filters that can be set to scan incoming e-mail and then perform a designated function with that e-mail. Such programs have been set up to scan for messages that do not contain a user's personal e-mail address and to filter such messages into a “hold for review” mailbox. By transferring messages that are not personally addressed, the system can be programmed to attempt to filter out spam.
Another approach to filtering unsolicited e-mail is described in U.S. Pat. No. 5,999,932 to Paul. In this patent, a user creates an inclusion list including identification data for identifying e-mail desired by the user. Data from one or more fields of incoming e-mail are compared with the identification data stored in the inclusion list. If no match is detected, the system performs at least one heuristic process to determine whether the e-mail may be of interest to the user. If the e-mail message does not satisfy any heuristic criteria, the message may be marked with a display code, such as “junk.”
Yet another approach to the problem of spam is provided by products that attach digital signatures to outgoing mail and that then monitor incoming mail looking for valid signatures. One such product is available commercially as AuthentiMail™, from Omnipoint Technologies, Inc. This system uses an intermediary server between the external Internet and an internal mail server. Before an e-mail is delivered to the Internet, a signature is attached to the message to protect the user's e-mail address. If a third party server tries to forward the message or compile the sender's name in a mailing list, however, the signature is invalidated to prevent spamming.
While the above-described techniques do prevent and/or attempt to minimize the harmful effects of spam, they require complex and costly software and/or servers that are difficult to set up and maintain.
There remains a need for a simple, yet effective way of restricting unsolicited e-mail within an enterprise e-mail environment. The present invention addresses this need.
BRIEF SUMMARY OF THE INVENTION
The present invention is a method and computer program operative in an e-mail server for reducing unsolicited e-mail in an enterprise computing environment. According to the invention, e-mail is accepted for delivery to e-mail clients only if it is from an address that has been verified by an e-mail server and/or approved by a recipient. When an e-mail from a particular address is received at the e-mail server for the first time, the server automatically issues an e-mail to the address to request that the sender verify the authenticity of the original message. If a return acknowledgement is received within a given time period, the e-mail is deemed to be acceptable and delivered to its intended recipient within the enterprise. Mail messages from previously-verified addresses need not be rechecked.
According to a preferred embodiment, a list of approved addresses is maintained at the e-mail server for each user, preferably without requiring the user's interaction. The address of any outbound e-mail sent from an e-mail client is automatically added to the user's approved address list. An inbound e-mail having a sending address that is seen for the first time is delivered to a holding queue instead of being delivered to the intended recipient. The server responds to the inbound e-mail by issuing an e-mail back to the unknown sending address, requesting a return acknowledgement. If the acknowledgement is received within a given time period, the e-mail is released from the holding queue and delivered to the intended recipient. If, however, an acknowledgement is not received within the given time period, it is flushed from the holding queue. Using this method, spam e-mail accumulates in the user's holding queue instead of being delivered to the user's inbox because spamming is typically accomplished by automated routines that cannot or do not respond to the e-mail's server's request for acknowledgement.
In a representative embodiment, a method of restricting unsolicited e-mail is responsive to receipt of an e-mail for determining whether a sending address associated with the e-mail is on a given list of approved addresses. If not, an e-mail is issued to the sending address requesting a return acknowledgement. The e-mail is then directed to a holding queue pending receipt of the return acknowledgement. The e-mail is deleted from the holding queue if the return acknowledgement is not received within a given time period, indicating that it is likely a spam message. On the contrary, the e-mail is released from the holding queue upon receipt of the return acknowledgement within the given time period. In such case, the sending address is then added to the given list of approved addresses and is not rechecked if a subsequent e-mail (originating from the same address) is received at the e-mail server.
If desired, once an e-mail having a particular sending address has been approved for delivery to an intended recipient and the sending address added to the approved address list, any e-mail that originates from the same domain may also be added to address list.
According to a more particular aspect of the invention, an e-mail server includes a mail transport agent for receiving inbound e-mail intended for a given e-mail client, and an anti-spamming agent associated with the mail transport agent for blocking unsolicited e-mail. The anti-spamming agent includes code for generating a list of approved addresses for each e-mail client, and code responsive to receipt of an e-mail for a particular e-mail client for determining whether a sending address associated with the e-mail is on the e-mail client's given list of approved address. The anti-spamming
Drummond Kirk
Fields Duane Kimbell
Gregg Thomas Preston
Kolb Mark Andrew
Bailey Wayne P.
LaBaw Jeffrey S.
Maung Zarni
Yee Duke W.
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