# E17050 — MailboxRetentionRebaseInProgress

The mailbox is still applying its previous retention tier change.

- **HTTP status**: `409`
- **Type**: `conflict_error`
- **Name**: `MailboxRetentionRebaseInProgress`

## What to do

Wait for the current change to finish, then lower the tier again. Large mailboxes can take hours. You can still raise the tier to one your plan permits.

## Related

- [Idempotency](/docs/api/idempotency): safe retries and key reuse rules
- [E17xxx — Agent mailboxes](/docs/api/errors/E17xxx): every code in this range
- [Errors](/docs/api/errors): the full wire contract, status mapping, and error catalog
- [Error handling](/docs/guides/errors): branching on `type` and `code`, validation details, and `vendor_code`