For example, we estimate that one message out of a thousand that scores 7 SpamAssassin points is actually not spam (although it will usually be mailing list mail that "looks like" spam, not personal mail). So SpamAssassin can very occasionally lead to "false positives". 1.8 points isn't nearly enough for a message to be considered "spam" by itself, but it's remotely possible that an unlucky combination of several such things can give a perfectly innocent message a high SpamAssassin score. Most such messages are spam, even though some aren't. It can misidentify borderline messages that "look like" spam but really aren't, such as messages from friends sending Viagra jokes, or messages containing legitimate information about prescription drugs, or messages in which the sender's mail server had some sort of technical configuration problem that made it appear that it was "forging" someone else's domain name.Īs a real-world example, SpamAssassin adds 1.8 points to the score of a message with a subject that contains only capital letters. SpamAssassin is fairly accurate in identifying spam that makes it past our blocking filters, but it's not perfect. We do block most messages with very high SpamAssassin scores (over 14 for the "Standard Spam Filtering" setting), but we don't block messages with scores lower than that, even when SpamAssassin adds “X-Spam-Status: Yes” and “X-Spam-Flag: YES” headers. Why aren’t messages with high SpamAssassin scores completely blocked? Remember that SpamAssassin isn't 100% perfect (see the next section for details about that), so be sure to glance at the contents of the "Spam" folder every so often. If you want to make it more sensitive, you could use fewer asterisks in the rule (but that may lead to more "false positives"). This rule will make our mail servers examine any new messages to see if they have a SpamAssassin score of 7 or more (because those messages have seven or more asterisks in a "X-Spam-Level" header). Create a rule where the “X-Spam-Level” header contains *******. (This creates a simple Sieve email filter behind the scenes.)įirst of all, create a folder called something like "Spam" if you haven't already done so: You can use the SpamAssassin scores to filter probable spam using Webmail filtering rules. How can I use SpamAssassin scores in Webmail? In our experience, a message with a score of 7 or more is almost always spam, so one option you might want to consider, if your mail program allows it, is to add a rule that looks for messages that contain at least seven asterisks in the " X-Spam-Level:" header and files them in a "Spam" folder. The reasons are often technical: in this case, most of the score was due to the spammer's computer impersonating, for example. This message received a SpamAssassin score of 9 for the six different reasons shown. * 0.5 FORGED_YAHOO_RCVD 'From' does not match 'Received' headers * 3.0 FORGED_RCVD_NET_HELO Host HELO'd using the wrong IP network * 3.0 NO_RDNS_DOTCOM_HELO Host HELO'd as a big ISP, but had no rDNS * 1.5 HTML_IMAGE_ONLY_04 BODY: HTML: images with 200-400 bytes of words * 0.6 HTML_WEB_BUGS BODY: Image tag intended to identify you X-Spam-Report: SpamAssassin headers added by. HTML_IMAGE_ONLY_04, HTML_MESSAGE, HTML_WEB_BUGS, Tests=FORGED_RCVD_NET_HELO, FORGED_YAHOO_RCVD, HTML_20_30, Here are some sample "headers" from a spam message: For example, our Webmail system and Microsoft Outlook allow you to create rules based on message headers. You can create rules in most mail programs to sort mail that receives high SpamAssassin scores. The headers are usually invisible unless you show the "full Internet headers" in your mail program. SpamAssassin adds special "headers" to each message showing the details of the score it calculated. SpamAssassin looks at the actual content of each message and assigns it a "spam level" score based on how much it "looks like" spam for example, messages that mention "Viagra" will receive a higher score than messages that don't. How can I get more information about SpamAssassin?.Why aren’t messages with high SpamAssassin scores completely blocked?.How can I use SpamAssassin scores in Webmail?.(A few messages are not scanned by SpamAssassin for various reasons, such as their size, and therefore won't have any extra SpamAssassin headers.) The headers are added by a scanner called SpamAssassin that examines most incoming messages that make it past our other spam filters. Advanced users might notice that the "full headers" of some mail you receive through our Web hosting service include headers named X-Spam-Status, X-Spam-Level, X-Spam-Score, X-Spam-Flag and X-Spam-Report.
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