// Glossary
Bounce Rate
The percentage of sent emails that fail to deliver, a key signal mailbox providers use to judge a sender.
Definition
Bounce rate is the share of emails in a send that fail to reach the inbox, expressed as bounces divided by total sent. It combines hard bounces (permanent) and soft bounces (temporary). High bounce rates tell mailbox providers your list is stale or unverified, hurting sender reputation and deliverability. Keeping bounce rate low through pre-send verification and list hygiene is essential for inbox placement.