# E17048 — MailboxRetentionTierNotInPlan

The requested retention tier is not included in your plan.

- **HTTP status**: `402`
- **Type**: `billing_error`
- **Name**: `MailboxRetentionTierNotInPlan`

## What to do

Upgrade to a plan that includes the tier, or contact sales for an exception.

## Related

- [Billing and usage](/docs/guides/billing-and-usage): balance, plans, and top-ups
- [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`