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POST
Add a mailbox domain

Authorizations

Authorization
string
header
required

Sendmux API key. Use a root API key for Management API routes, or a mailbox credential for Mailbox API routes. Obtain keys from the dashboard under API Keys.

Headers

Idempotency-Key
string

Client-chosen unique key to safely retry the request. Cached for 24h per (team, endpoint, key). Different body with same key returns 409 idempotency_conflict.

Maximum string length: 255
Example:

"domains-create-20260424-001"

Body

application/json
domain
string
required

Fully qualified domain name. Must be lowercased and domain-only (no scheme).

Example:

"mail.acme.com"

mode
enum<string>

Domain usage mode. Defaults to send_receive when omitted.

Available options:
send_only,
send_receive
Example:

"send_only"

Response

Domain created. The response carries a Location header pointing at the canonical GET URL for the new domain.

meta
object
required
ok
enum<boolean>
required
Available options:
true
data
object
required