Why did my email fail in certain spam filters?

No matter who you are, if you send email campaigns you will usually run into spam filter issues. On average,  10-20% of your emails will get blocked due to over zealous spam filters and user settings. The unfortunate fact is that innocent email marketers who send permission-based emails get spam filtered all the time. The best way to be successful is to understand how filters work, and minimize the chance your email has of encountering these issues.

Spam filters look at a long list of criteria. In particular, they scan for phrases like “CLICK HERE!” or “FREE! BUY NOW!” They assign points each time they see certain phrases. Some criteria causes higher points than others.

Here are some sample criteria from Spam Assassin:

  1. Talks about lots of money (.193 points)
  2. Contains urgent matter (.288 points)
  3. Money back guarantee (2.051 points)
  4. Why Pay More? (1.249 points)

The list of  criteria is constantly growing and adapting because spam filters learn what junk looks like every time someone clicks “This is spam” in their email program. Spam filters even sync-up with each other online to share what they’ve learned. Avoiding these common mistakes can help you have the best chance of email deliverability:

  1. Using phrases, like “Click here!,” “Once in a lifetime opportunity!” or  “Free”
  2. Multiple exclamation points!!!!!!
  3. USING ALL CAPS (especially in the subject)
  4. Coloring with bright fonts like red, or green
  5. Creating an HTML email that’s nothing but one big image, with little or no text (since spam filters can’t read images, they assume you’re a spammer that’s trying to trick

Notice with all caps and exclamation points, the email failed more filters that the same identical email with a different subject.