How bounces and complaints are handled

A clean list is the cheapest deliverability win there is. Mule Mail protects yours automatically.

• Hard bounce (the address does not exist): added to your suppression list immediately and excluded from every future send across the workspace.
• Soft bounce (mailbox full, server busy): retried up to three times, then treated as a hard bounce.
• Complaint (the recipient hit "spam"): suppressed immediately. If complaints pass 0.1% on a campaign, you get an alert.

You cannot send to a suppressed address. This is deliberate. Sending to known-bad addresses is how a domain reputation dies.