create_mailbox
Create a sending mailbox on a verified domain, with reply capture wired up automatically.
›Create sarah@mail.acme.com on our verified domain with display name "Sarah at Acme" and start gradual warmup.
What it does
Adds a sending address on a domain that has already verified. When the zone is on the operator Cloudflare account, the inbound routing rule for reply capture is provisioned as part of creation rather than left as a manual follow-up.
New mailboxes land in warmup `pending`. They are not send-eligible yet, and that is the point — the next decision is whether to ramp gradually with `start_warmup` or, for an inbox with genuine existing history, bypass the ramp with `skip_warmup`.
Set `daily_limit` if you want this mailbox to stay below the default ceiling. Setting it higher will not help; the pipeline caps it anyway.
Parameters
| Name | Type | Notes |
|---|---|---|
| domain_id * | string | Must be a verified domain. |
| email * | string | Full address on that domain. |
| display_name | string | The From name recipients see. |
| daily_limit | integer | Per-mailbox cap. The 30/day hard ceiling still applies. |
* required · Maps to POST /api/mailboxes
What comes back
The mailbox, its warmup state (`pending`) and reply-capture result.
The thing people get wrong
A real person should be reachable at the address. Recipients reply, and a bounce back from your own sending address is a worse signal than the campaign was ever going to be worth.
Use it with
More mailboxes tools
See all 22 tools and the connection string on the MCP server page.