# E10009 — MaxCustomHandlesExceeded

Your plan's allowance of custom inbox.ai handles has been reached.

- **HTTP status**: `422`
- **Type**: `validation_error`
- **Name**: `MaxCustomHandlesExceeded`

## What to do

Upgrade your plan for more custom handles, create the mailbox on your own receiving-enabled domain, or omit the local part to get a generated address. A deleted custom handle keeps its slot for 30 days (its restore window).

## Related

- [E10xxx — Quotas](/docs/api/errors/E10xxx): 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`