Bounce rate
The share of sent messages that bounced, counted by each platform in its own way; a high rate signals a poorly kept list to providers and sending platforms.
What it means
Platforms define it differently, so numbers are only comparable within one platform. Amazon SES, for example, counts only hard bounces to domains the sender has not verified, leaving out temporary failures such as a full mailbox and bounces caused by blocked IPs. It recommends staying below 2%, places an account under review at 5% and may pause sending at 10%.
Bounce rate mainly reflects list quality: addresses that do not exist enter lists through typos, old data, bought lists and scraping. Checking addresses when they are collected and removing hard bounces at once keep it low, and Google's guidelines ask senders to unsubscribe recipients after multiple bounces.
Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- Amazon SES Developer Guide: Enforcement FAQs (bounce rate)docs.aws.amazon.com
- Google, Gmail Help: Email sender guidelinessupport.google.com
All 432 terms in the glossaryThe wiki: blocklists and bounce codes