I get this question often: Why are my emails being reported as spam? I comply with CAN-SPAM, I send only to people who opt-in, and I think I'm doing everything right. What's going on? How can I possibly still be identified as a bad guy by the ISPs?

Well, here's why. Tamara Gielen capably summarizes the recent MarketingSherpa/Q Interactive survey that talks about why recipients report mail as spam. According to the survey, the top five reasons people report a message as spam are as follows:
  1. Didn't sign up to receive email from sender (52%).
  2. Email received was not of interest (41%).
  3. Receive too much email from the sender (25%).
  4. Receive too much email from senders in general (20%).
  5. Found email offensive (15%).
What does that all mean? It means that respecting subscriber permission is still the most important thing you can to do prevent spam complaints. But, it also means that permission alone isn't enough insurance against spam complaints. You need to ensure your emails are useful (#2 - speaks to subscriber engagement), ensure that your sending frequency is appropriate (#3), never buying or selling lists (#4, the tragedy of recipient dilution), and that you never send emails that are so far off the mark that you upset your subscriber base (#5).

Regardless of why recipients report your mail as spam, ISPs still count those votes against you. That's why it's up to you to ensure that you're doing all the right things, if you want to remain a sender in good standing. Failure to observe these best practice guidelines means you're far more likely to find your email blocked, filtered, or delivered to the junk folder.