OKDork

Active list size, not total list size, is the metric that matters

Kagan says the number that matters is not your total email list but your active list: people who opened or clicked within the last 3 months. He had 175,000 lifetime OKDork subscribers but only 55,000 active.

“But the second thing is, the number that's the most important is not your email list size, it is your active email list size. So it is the amount of people within 3 months that have opened and clicked your email. Because, you know, I've had hundreds of thousands. I think in my total lifetime of OKDork, I've had 175,000 subscribe to the newsletter. My active audience is only 55. Think about that.”

Steal thisTrack active subscribers (opened/clicked in last 90 days), not raw list size, and sunset the dead weight.