Which address does the email API send from?

From an inbox on your own verified domain, such as hello@studio.example. The request names the inbox with its inb_ ID, which you can copy from Inboxes for the API on the same page.

Does the email API use my email credits?

Yes. Each email sent through the API uses your email credits and a little of your plan's AI usage. A send is refused with an error when the workspace has no email credits left or has run out of AI usage.

Can I limit a key to one inbox?

Yes. When you create a key, leave it on Any inbox or pick the inboxes it can send from. A key limited to one inbox can't send from the others.

What if an email API key leaks?

Open the key's menu in Email API keys and choose Revoke. Apps using it stop sending right away, and you can create a new key for them.

Which plans include the email API?

Any plan that can use a verified custom email domain: Cadet, Voyager, Specialist, Commander and Enterprise. The inbox you send from must be on a verified domain.

Inbox & callsWorkflows

Send email from your own app with the Workspace369 email API

Owners and admins can create send-only email API keys, so your own app or website sends email from a verified domain with one API call. Each send uses your email credits.

Cut-paper illustration of a large amber key lying across a sealed envelope, with a smaller teal envelope flying away on an amber ribbon, beside the Email API keys page listing two keys and two inboxes.

Let your own app or website send email from your verified domain

Workspace369 now has an email API. Your own app or website can send an email from an inbox on your verified custom email domain with one call to POST https://mcp.workspace369.com/v1/email/messages. The request names the inbox it sends from, one recipient, a subject and a text or HTML body, and attachments are allowed. The call carries an email API key as a bearer token, and an optional Idempotency-Key header makes a retry safe.

Workspace owners and admins with AI connections access create the keys in Settings → Integrations → For developers → Email API keys. Create key asks for a name, such as Booking site, and lets you limit the key to chosen inboxes or leave it on Any inbox. The key is shown once, so copy it into your server's secrets. It can only send email, and it should never go in website or phone app code. Creating a key can ask you to sign in again first. Each key in the list shows whether it is on Any inbox or limited to some inboxes, and when it was last used, and Revoke in its menu stops any app using it from sending right away.

Below the keys, Inboxes for the API lists the active inboxes on your own domain, each with its inb_ ID to use as from.inbox_id. Copy ID copies it. An inbox whose domain isn't verified yet is marked Domain not verified and can't send. Each email sent through the API uses your email credits and a little of your plan's AI usage, and a send is refused with a clear error when the workspace has no email credits left or has run out of AI usage. It works on any plan that can use a verified custom email domain, which is Cadet and above.

Create send-only email API keys, shown once, limited to chosen inboxes or any inbox
Copy an inbox's inb_ ID for from.inbox_id
Revoke a key and the app using it stops sending right away

Create a send-only key limited to one inbox, copy it once, then copy an inbox ID. Example data.

Where to find it: Settings
Integrations
For developers
Email API keys
Plans: Every plan
Learn more: Send email with the Workspace369 API Add addresses on your custom email domain The Builder API on every plan

Quick answers

Who can create email API keys?: Workspace owners and admins with AI connections access. In Settings → Integrations → For developers → Email API keys, choose Create key, name it and copy the key. It is shown only once.
Which address does the email API send from?: From an inbox on your own verified domain, such as hello@studio.example. The request names the inbox with its inb_ ID, which you can copy from Inboxes for the API on the same page.
Does the email API use my email credits?: Yes. Each email sent through the API uses your email credits and a little of your plan's AI usage. A send is refused with an error when the workspace has no email credits left or has run out of AI usage.
Can I limit a key to one inbox?: Yes. When you create a key, leave it on Any inbox or pick the inboxes it can send from. A key limited to one inbox can't send from the others.
What if an email API key leaks?: Open the key's menu in Email API keys and choose Revoke. Apps using it stop sending right away, and you can create a new key for them.
Which plans include the email API?: Any plan that can use a verified custom email domain: Cadet, Voyager, Specialist, Commander and Enterprise. The inbox you send from must be on a verified domain.

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