Five Evaluation Criteria for Data Loss Prevention ToolsThoughts on Gartner's considerations for narrowing down your list:Channels. How many protocols does the product cover, and is it capable of decoding the protocol? The market is rapidly moving toward multiple-protocol decoders, Gartner says.Blocking. Not all products perform blocking, and some block only on certain channels, though Gartner sees the market moving toward products that will block all channels.E-mail. Most products block e-mail first and enable quarantining, rerouting, blocking, encryption and other more complex handling rules, Gartner says. Few products today monitor internal e-mail, but some provide Microsoft Exchange or Lotus Notes integration. Users should be cautious of products that monitor e-mail passively or block SMTP traffic by resetting TCP connections, which provides no feedback to the sender and can cause performance issues, according to Gartner.Detection techniques. Options include rule-based detection, document fingerprinting, database matching and statistical analysis. "If you're looking for things like Social Security numbers, that's not a hard thing to do, but when you start asking for other kinds of data, it gets harder," says Jon Oltsik, senior analyst at Enterprise Strategy Group. "Some products have more kinds of classifications than others\u2014financial data, credit card data or whether people have hacking scripts on their desktop."Data-at-rest content discovery capabilities. Some products automate the discovery of where sensitive data resides. Oltsik says, "Data travels from person to person, gets attached to e-mails, is downloaded in flat files and put in spreadsheets or databases. Understanding where your data is [is] an important first step."