How Spam Filters Work?
Spam filters look at some predetermined criteria to decide if your email is junk. They score that criteria and if you’re message reaches a high enough number on the score, your email is relegated to a “bulk”, “junk” or “spam” folder.
One of the most popular spam protection companies, Spam Assassin, publishes the tests they perform on emails and the corresponding scores. Here are a few examples:
- Subject starts with a dollar amount (.600 points)
- Subject talks about losing pounds (1.927 points)
- Similar addresses in recipient list (2.499 points)
- Message begins “Dear Friend” (2.683 points)
- Message talks about how to be removed from mailings (2.907 points)
You can see how frustrating writing emails can be when one of the requirements of the CANN-SPAM Act, making sure there’s a clear communication of how the recipient can remove themselves from mailings, also penalizes you.
Further complicating the matter is that every ISP has their own list of criteria, and own calculation of the threshold that condemns your mail.