Why you need to keep false-positives to a minimumWritten by Brett Callow on February 5, 2009
Fact: spam cannot be blocked with 100% accuracy. No matter which anti-spam product you use and no matter how many hours you spend configuring it, it’s absolutely inevitable that some spam will slip through the net and that some valid email will end up being blocked. While a few missed spam emails may not be too much of a problem, a few blocked valid emails can be extremely damaging. I mean, who wants to deal with a company that doesn’t reply to emails? But the consequences of wrong trashed emails can be worse than simply lost business and damaged customer relationships.
In 2007, the Washington Post reported the case of Franklin D. Azar & Associates. The basics of the story are as follows. The law firm ramped up the settings on its anti-spam in order to block pornographic emails which had been reaching users’ desktops. The appliance started blocking the unwanted messages, but it also started blocking emails from the United States District Court for the District of Colorado which caused Azar and Associates to miss a court hearing. The judge subsequently ordered that the Azar and Associated pay the costs of the opposing counsel who did appear. The judge commented that “It is incumbent upon attorneys to adopt internal office procedures that ensure the court’s notices and orders are brought to their attention once they have been received,” and “That it would have been a very simple task to whitelist the United States District Court for the District of Colorado’s domain name of “cod.uscourts.gov” to ensure that such emails with this domain name would always be received.”
Yup, the judge was right when he said that it would have been a “very simple task to whitelist the United States District Court for the District of Colorado’s domain name.” What wouldn’t have been so simple, however, is to whitelist each and every one of the law firm’s contacts. Creating and managing whitelists can be an extremely time consuming process. Exchange Server 2007 eases the burden somewhat with a feature known as Safelist Aggregation. From Microsoft:
In Microsoft Exchange Server 2007, the term safelist aggregation refers to a set of anti-spam functionality that is shared across Microsoft Office Outlook and Exchange. This functionality collects data from the anti-spam Safe Recipients Lists or Safe Senders Lists and contact data that Outlook users configure and makes this data available to the anti-spam agents on the computer that has the Edge Transport server role installed. Safelist aggregation can help reduce the instances of false-positives in anti-spam filtering that is performed by the Edge Transport server.
But while Safelist Aggregation does indeed make things somewhat easier, it’s certainly not a perfect solution as it is reliant upon users having whitelisted their contacts – and that’s something they often do not do. Furthermore, even if users have whitelisted their contacts, they may have whitelisted domains rather than addresses and you’ll probably not want to aggregate that data (you don’t want emails from Hotmail addresses to be unfiltered, do you?).
There is, however, an alternative. Some anti-spam products include a feature which, when turned on, enables the addresses of emails to which users have replied to be automatically whitelisted. This will not eliminate the possibility that valid emails will be blocked, but it will make it substantially less likely. When the time comes for you to go shopping for an anti-spam solution, this is certainly a feature which you should add to your “must-have” list.