Definition
Spam complaint rate is the share of delivered emails that recipients mark as spam. Gmail and Yahoo both say to keep it below 0.3%.
Providers measure it from their own users' behaviour, not from anything you send, which makes it the signal cold senders control least directly and break first. Google reports it in Postmaster Tools and says to stay below 0.10% and avoid ever reaching 0.30%; Yahoo says to keep it below 0.3% of mail delivered to the inbox. Illustrative example: a team sends 2,000 cold emails to Gmail addresses in a day and 6 recipients click Report spam. That is 6 divided by 2,000, or 0.3%, right at the ceiling. Had only 2 people reported, the rate would be 0.1%. Nothing about the volume changed between the two outcomes, only who received the email. The usual causes are loose targeting, a first line that never says why the recipient was chosen, and an unsubscribe link that is hard to find, which pushes people towards the spam button instead. Lowering the rate is mostly a list-quality job, which is why it connects directly to sender reputation: a high complaint rate lowers it, and a low reputation means fewer emails reach the inbox at all. Provider calculations differ in detail, so use the figure in Google Postmaster Tools rather than your own arithmetic as the source of truth.
Frequently asked questions
What is a good spam complaint rate for cold email?
Below 0.10% is the safer target. Google tells senders to stay under 0.10% and never reach 0.30%, and Yahoo sets 0.3% as its ceiling. In practice that means fewer than one complaint per thousand delivered emails, which cold senders only reach with tightly targeted lists and an easy, visible unsubscribe.
Where can I see my spam complaint rate?
Google Postmaster Tools reports the spam rate Gmail measures for your sending domain, once you verify the domain and send enough mail for data to appear. It is the figure Google's own guidelines point to, so check it weekly and treat it, not your sending tool's estimate, as the one that counts.
How do I lower my spam complaint rate?
Start with the list: send only to people who plausibly have the problem you solve, and make the first line say why you are writing to them. Then make unsubscribing obvious and instant, since recipients who cannot find the link tend to hit report spam instead of replying.
Where this comes from
Read: Cold Email Deliverability: Why Your Emails Land in Spam (And How to Fix It)