Email bounces
Hard bounces suppress the address. Events stay on the cluster.
When a destination refuses a message, PostShiba records a bounce event on the cluster. A hard bounce also adds the address to your suppression list, so you stop sending to it.
What each failure does
| Failure | Event | Adds a suppression? |
|---|---|---|
| Hard bounce: the mailbox or host does not exist, or the mailbox has moved | bounce |
Yes, reason Bounce |
| Soft failure, such as a full mailbox | deferred while PostShiba retries |
No |
| Message expired before delivery | bounce with reason expired |
No |
| Spam report from the recipient | spamreport |
Yes, reason Spam report |
The suppression lands on the tenant that sent the message. Later sends skip that address. A send to only that address returns 403 suppressed. See Errors.
Read a bounce
Open Activity → Events in the sidebar, then open the event. The event page shows the SMTP code, the enhanced code, the bounce classification, the bounce reason, and a plain explanation you can paste to a customer. See How do I read a bounce reason?.
Where bounces arrive
Bounces and spam reports come back to the domain's return-path host. PostShiba matches them to the sending domain and stores the event on your team. See Return-path.
Event fields are on Events.