Spam complaint rate

Spam complaint rate is the percentage of delivered emails that recipients mark as spam. Google's bulk sender rules require it to stay under 0.3 percent, with 0.1 percent as the target, and a domain over the line gets throttled.

This is the single number that ends cold email programs. Bounces and unsubscribes are survivable. A spam complaint rate above 0.3 percent at Gmail puts a domain into a penalty that can take weeks to climb out of, and the emails that were landing stop landing in the meantime.

Three things drive it up. Sending to people who have no reason to hear from you, which is what a title-based list does. Sending too much, because volume is what turns a mild annoyance into a complaint. And making it hard to say no, because a recipient who can't find an unsubscribe marks it as spam instead. A reply-to-unsubscribe line that's honored the same day keeps most complaints from happening.

An example

A program sends 5,000 emails a month to a purchased list and gets 22 spam complaints. That's 0.44 percent, over the line, and the domain gets throttled at Gmail the following week. A signal-based program sends 1,200 emails the same month to companies where something just happened and gets one complaint. That's 0.08 percent, and the domain's fine.

How to measure it

Google Postmaster Tools shows the rate per domain for Gmail recipients. For Microsoft, SNDS shows complaint data by IP. Track it per sending domain, weekly, and rest any domain that goes over 0.2 percent before it reaches 0.3.

Related terms

Email deliverability · Cold email bounce rate · Sending domain · CAN-SPAM

If you want this run for you, see our cold email agency.