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There are a few things to keep in mind when you get a report of an overall increase in spam from one of your clients:
1: The efficacy of our filter is a matter of percentages, not raw numbers. Over 90% of all email traffic worldwide is spam. The longer an email address is used, the more spam it will receive. There are a number of reasons for this, but the concept is the same as it is for paper junk mail you receive in your “real” mailbox. You get more mail the longer you stay at the address, and a lot of it is junk simply because a lot of ALL mail is junk. It’s not an error anywhere; this is normal (albeit annoying) behavior.
2: We are constantly developing and updating rules. We don’t remove rules, so there will not be an increase in spam because of us making our filter less strict. Our filter uses a lot of algorithms to assign every message a spam score. The spam engine analyzes message content to determine if most people would find it offensive. Message format, layout, design, and vocabulary are considered as part of thousands of checks on message attributes, including:
- To field
- Subject field
- Header fields
- Email format, design, and layout
- Vocabulary, word formatting and word patterns
- Foreign language detection
- SMTP envelope content and analysis
- Country trace
- Image layout classification
- Hyperlink analysis and comparison
- Contact verification
The spam engine also parses words into pieces, which allows the detection of similar vocabulary even if the words are not exact matches.
We also conduct Bayesian analysis of message content. The engine then uses its AI technology to ensure that it "learns" over time as spam changes.
3: The more examples you give us, the better. Updating the filter is related to trends, not instances. One spam message getting through isn't very helpful to us, but if there are 50 messages, we can look through them to spot the commonalities. The best thing to do is to get a bunch of .msg files, zip them up, and forward them to email@example.com. The spam emails that are forwarded to us will be analyzed for inclusion into our filters
Hopefully that helps to clarify a few things. Note that this isn't to discourage you from sending us samples – in fact, please do send us samples! That’s how our spam engine learns. Just be sure to send us more than a handful of them. A good rule of thumb is that if you're sending fewer than 10 messages, you’re better off using your blacklist or an Outlook rule.
Also, if you’re getting several of them with the same subject line, you can block the message using the subject line filter.
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