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POST

Body

string | string[]
required
Recipient email address or array of recipient addresses. At least one recipient is required. Each address may be up to 320 characters.
string
required
Email subject line. Maximum 500 characters. CRLF characters are stripped automatically.
string
HTML body of the email. Maximum 10 MB. At least one of html or text is required.
string
Plain text fallback body. Maximum 10 MB. At least one of html or text is required.
string
Override the sender address. Must be a valid email address. When omitted, Commune resolves the sender from the inbox_id or domain_id provided. If neither is given, the default sending address for your account is used.
string
ID of the inbox to send from. Commune automatically resolves the from address and domain from this inbox. Recommended over domain_id when you have per-agent inboxes.Accepts either inbox_id or inboxId.
string
ID of the domain to send from when no inbox_id is provided. Commune constructs the sender address using your account’s default local part and this domain.Accepts either domain_id or domainId.
string
Existing thread to reply within. When set, Commune automatically sets In-Reply-To and References headers so the message threads correctly in the recipient’s email client. The subject is also prefixed with Re: automatically.
string | string[]
CC recipients. Accepts a single address or an array.
string | string[]
BCC recipients. Accepts a single address or an array.
string
Custom Reply-To address. When omitted, Commune sets a routing-token-encoded Reply-To automatically so inbound replies map back to the correct thread. Accepts either reply_to or replyTo.
string[] | object[]
Attachments to include with the email. Each element can be either an attachment_id string (from the Upload attachment endpoint) or an inline attachment object.
object
Custom email headers as a key-value map. Keys and values are sanitized (CRLF stripped). Standard headers like Message-ID, In-Reply-To, and References are managed by Commune and will be overwritten.

Response

object
object
Present only when some recipients were warned, rejected, or suppressed. A non-null validation object does not mean the send failed — it means at least one recipient had an issue while others were sent successfully.
Last modified on March 19, 2026