Note: this is an experimental extension. We always recommend to use a professional delivery service to send your marketing email and get the bounces correctly managed. We cannot grant the extension will be able to detect all kind of bounces.
When a message is sent to an invalid or unreachable address, most of the times you’ll receive back a delivery error message as response. If correctly formatted, those error notification messages contains a set of data, called DSN (delivery status notification) with information about the kind of error (temporary, permanent and so on).
The Bounce extension tries to analyze those messages and find out if is has been generated by an email address in your database. If so, it will be marked as “bounced” and never contacted again.