Complaint Rate
The percentage of people who mark your emails as spam. It shows how many subscribers see your message as unwanted and affects whether future emails reach the inbox.
Also known as Spam Complaint Rate, Abuse Rate
Complaint rate is the share of people who hit the spam or junk button on your email. It shows how many subscribers feel your message does not belong in their inbox. Email providers use this signal to decide if they trust your future sends.
A low complaint rate helps your emails reach the inbox more often. When that number climbs, providers start moving more of your messages into spam. That hurts opens, clicks, and revenue. It can take weeks or months to repair that damage.
Aim to keep complaint rate under 0.1 percent, or one complaint for every 1,000 emails. Send only to people who clearly asked to hear from you. Make it easy to unsubscribe so an unhappy reader can leave instead of pressing spam.