# What are sender bounces?

> A sender bounce means the sending mailbox was rejected — quota exceeded, mailbox disabled, authentication failed — not that the recipient was invalid. Fix the sender before you resume volume.

Source: https://emailpal.io/help/sender-bounces

## Recipient bounce vs sender bounce

- **Recipient bounce** — their side refused the address (disabled, full, does not exist). Clean the list.
- **Sender bounce** — *your* mailbox was not allowed to send. The recipient never had a chance.

Sender bounces show up as 5.7.x policy errors, quota exceeded, authentication failures, or "sender rejected" in a sequencer.

## Common EmailPal-related causes

- Hit the [daily cap](/help/sending-limits-per-mailbox) and the remote said quota
- Mailbox deleted or password rotated and the sequencer still has the old SMTP secret
- Warming or sending held after a [warmup bounce](/help/warmup-bounce-and-disabled-warmup)
- DNS no longer valid, so the receiving server treats you as unauthenticated

## What to do

1. Export fresh credentials. [Export mailbox credentials](/help/export-mailbox-credentials).
2. Confirm the mailbox still exists.
3. Confirm DNS. [DKIM not validating](/help/dkim-not-validating).
4. Resume only after a test to a seed you control.

## FAQs

### Does EmailPal auto-replace burning mailboxes?

Pre-warmed inventory is claimed as a set; we do not silently swap addresses under you. If a hosted mailbox is dead, delete it and provision another, or claim a new pre-warmed domain.

## Need more help?

[Why emails go to spam](/help/why-emails-go-to-spam) and [open a ticket](/help/open-a-support-ticket).