sendEmail sends custom content or a published Resend template. It supports
complete recipient fields, attachments, headers, tags, topics, scheduling, and
request idempotency.
Example
automations/send-resend-welcome.automation.ts
Inputs
to accepts one address or up to 50 addresses. Optional cc, bcc, and
replyTo accept one or more addresses. For custom content, from, subject,
and at least one of html or text are required. For a template, provide
template: { id; variables? } and do not provide html or text; the published
template may supply sender and subject.
Optional fields include headers, scheduledAt (natural language or ISO 8601),
topicId, and tags. Tag names and values allow letters, digits, _, and -
and are limited to 256 characters. Template variable names have the same basic
character set without dashes; values are strings up to 2,000 characters or
numbers. idempotencyKey is retained by Resend for 24 hours and is limited to
256 characters.
Attachments are either { content, filename, contentType?, contentId? } with
base64 content or { path, filename?, contentType?, contentId? } with a public
URL. Resend enforces its provider size limits.
Output
Returns{ id: string }. Save the ID to retrieve delivery state, update a
scheduled send, cancel it, or correlate webhook events.