It seems that no method of communication is impervious to solicitation. Companies used the postal service and it was called "junk mail." They turned to telephones it was called "telemarketing." They used fax machines and it was called "junk faxes." Finally they utilized electronic mail and it was called "unsolicited commercial e-mail" (UCE), affectionately known as "spam."
The simple reason why UCE is so popular is that e-mail is very inexpensive for the sender. Unlike postal mail, where each copy must be printed and posted, or phone and fax, where each call must be paid for, it is possible to send a single e-mail with thousands of recipients. The burden for delivering this mail is borne by Internet service providers (ISPs) and eventually the recipient. This article does not discuss the legal actions to be taken to reduce UCE, but instead explains what technical steps are possible to reduce UCE.
A short technical explanation is necessary in order to describe the difficulty of eliminating UCE. E-mail, as used on the Internet today, is transferred using the Simple Mail Transfer Protocol. By design, no authorization or signatures are required to send e-mail. The result is that any person or machine can send e-mail that appears to come from anyone else. This is very similar to postal mail, where a person could type someone else's return address on an envelope. However, this can make filtering and blocking UCE difficult, if not impossible.
For most business users, reducing UCE can happen in three places: the recipient's e-mail client, the business's e-mail server, or the closest upstream ISP. The former are more expensive and time-consuming than the latter for the simple reason that the e-mail must be transmitted through more computers, and many e-mail clients are served by each e-mail server. However, individuals do not have control over their corporate mail servers or their ISP, and therefore may be forced to find their own solution. It is within this context that filtering options will be discussed.
You first must consider the e-mail client in order to determine what filtering capabilities are available. The most popular e-mail clients currently available for MS Windows and Macintosh computers are Microsoft Outlook, Netscape Communicator and Qualcomm Eudora. Outlook calls them "rules," Communicator calls them "message filters" and Eudora calls them "filters." Eudora has the most flexible of filtering options, followed by Outlook and then Communicator.
The options for mail filtering range from aggressive, where the goal is to delete as many UCEs as possible, to conservative, where the goal is to delete as few acceptable e-mails as possible. The most guaranteed method of filtering your mail is to accept e-mail only from authorized sources. This method would involve making a list of e-mail addresses from which you will accept e-mail, and remove all other mail.
A slightly less aggressive (but more automatic) method is to accept only e-mail messages that are addressed to you (through the To: or CC: headers). This can normally be done by a single filter rule within your e-mail client. Be aware of the hazards. This rule will not only dump UCE, but also any e-mail sent with you as a blind carbon copy, as well as most mailing lists to which you subscribe.
A mostly conservative method of filtering UCE is by dumping only e-mail from addresses known to send UCE. This is the most popular method, and is used by many ISPs, but has several major downfalls. The main problem is management. There are many thousands of companies sending UCE, and so this filter list must be updated frequently. Like the more aggressive methods, you may end up losing e-mail that was destined for you, if one of your friends has an e-mail account with a company that has other customers who send UCE.
As you can see, there is not a single simple solution to filtering e-mail. Fortunately, there are commercial solutions for filtering e-mail, on both an individual and a corporate level. If you are an individual or a SOHO (small office/home office) user, then free services such as Brightmail will do your filtering for you. If you are a corporate user who utilizes a standard POP3 e-mail account, then SpamKiller and SpamBuster are programs that can assist you with filtering using any of the methods described above.
If you are a corporate information technology manager, then several anti-virus and firewall solutions such as TrendMicro ScanMail and Network Associates Gauntlet offer UCE filtering. Without these solutions people are forced to handle UCE like they all handle junk mail: Throw each piece in the trash.
Gile is president of Web Services Group Inc., an Internet, software development and consulting business in Colonie.