The spam complaint rate is the share of recipients who press "Report spam" on your email. It's the strongest negative signal inbox providers use to judge a sender.
The numbers that matter
Google asks bulk senders to keep it under 0.1% and never let it reach 0.3%, the line above which email starts landing in spam or being rejected. Yahoo uses the same line. For cold email, aim for well under 0.1%: one complaint per thousand emails.
Why cold email gets complaints
- Emailing people who have nothing to do with what you sell.
- No obvious way to say no, so the spam button is the easiest exit.
- Too many follow-ups, or follow-ups after someone replied.
- Emails that read like mass marketing.
Keeping it low
Write to a narrow, relevant audience, make opting out easy, stop the sequence when someone replies and keep follow-ups to three or four. You can't see Gmail's complaint figures for cold email directly, so watch opt-outs and "remove me" replies as an early warning.