Three spam complaints per 1,000 emails is Gmail's limit

Gmail and Yahoo both say to keep your spam complaint rate below 0.3%. That's about three people per 1,000 clicking "Report spam," and Google advises staying well under it, not near it.

Quick setup

• Add your sending domain to Google Postmaster Tools and check the spam rate weekly.
• Pick your own tripwire, say 0.1%, and pause the campaign that pushed you there instead of sending harder.
• Make opting out easy. People who can't find the exit hit the spam button instead.

Low-volume senders may see no data in Postmaster Tools, so the easy opt-out matters even more for them.

Limits, tracking, and how to lower complaints: Cold email spam complaint rate.