Metrics
What is Spam Rate (Complaint Rate)?
The percentage of delivered emails that recipients mark as spam.
Spam rate, or complaint rate, is the share of delivered messages that recipients explicitly report as junk, usually measured against mail that reached the inbox. Providers track it through feedback loops and surface it in tools like Google Postmaster Tools. Google asks bulk senders to keep the user-reported rate below 0.3% and never let it average above 0.1%.
Why it matters for cold email
Spam rate is one of the strongest reputation signals and is especially unforgiving for cold email, where uninterested recipients readily hit report spam. Crossing provider thresholds triggers spam-foldering or outright blocks across your whole domain, so tight targeting and an easy opt-out are essential to keep complaints down.
Related terms
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