What is a bounce?

Bounces are undeliverable emails. They are usually separated into two categories: hard bounces and soft bounces.

Mandrill uses a specific set of heuristics to determine whether a bounce should be classified as hard or soft. Typically, permanent errors like non-existent mailboxes will get classified as hard bounces, while quota errors and other temporary issues are treated as soft bounces.

Mandrill handles bounces and reports them automatically in your account. Read more about how Mandrill handles bounces. Learn how to view bounce details in Mandrill.