What are Gmail’s complaint thresholds?

Gmail's complaint thresholds set clear boundaries for acceptable spam report rates. The target is keeping complaint rates below 0.1% (1 complaint per 1,000 emails). The maximum tolerable rate before serious consequences is 0.3%.

Exceeding 0.3% triggers aggressive filtering and potential rate limiting. Sustained high complaint rates can damage domain reputation severely, requiring weeks or months of clean sending to recover. Gmail measures complaints relative to delivered mail, not sent mail.

These thresholds apply to the overall complaint rate across all Gmail recipients, not per campaign. A single bad campaign can push you over the limit even if other sends perform well. Monitoring complaint rates through Gmail Postmaster Tools helps you catch problems before they trigger enforcement actions.