Sender reputation signals
The set of measurements a mailbox provider uses to decide how to treat your mail. Of these, the ones with published thresholds are the spam complaint rate and the authentication requirements in Google's sender guidelines.
In plain terms
What the receiving side already knows about you before it decides where your message goes.
Why it matters for deliverability
Reputation is not a number anyone publishes in full, so it is tempting to treat it as a mystery. The parts that are published — complaint rate thresholds and the authentication baseline — are the parts you can act on directly.
What to do about it
- Work on what is measurable: complaint rate, bounce rate, authentication pass rate.
- Keep sending volume and cadence steady rather than spiking.
- Verify addresses before sending, so bounce rate never becomes the signal that defines you.
Source
Google — Email sender guidelines
“Keep spam rates reported in Postmaster Tools below 0.10% and avoid ever reaching a spam rate of 0.30% or higher.”
Checked 2026-08-29
Go deeper
Definitions reviewed 2026-08-29. Spotted something wrong? Tell us.
See how your own mail is handled
Run a real message through MailTester and read the authentication results, spam score and delivery signals described on this page against your own domain.