send email

Builds an RFC 5322 message and hands it to the SMTP server on the connection. Use this to deliver through your own MTA (Exim, Postfix) rather than a hosted API.

Composes a complete MIME message and submits it over SMTP. Body structure is chosen from what is filled: text+html become multipart/alternative, inline_images wrap that in multipart/related, attachments wrap the result in multipart/mixed, and a single body alone is sent as one part. text is derived from html by stripping tags when the text pin is empty. Non-ASCII header values are RFC 2047 encoded; bodies are quoted-printable or base64 so the wire stays 7-bit safe; lines end CRLF. The ENVELOPE is from + to + cc + bcc; Bcc never appears in the headers, and the headers pin refuses From/To/Bcc/Message-ID overrides (Message-ID comes from the message_id pin only, so the message_id out-pin always reports the delivered id). Every header value is sanitized against line breaks; message_id, an inline image cid and an address net/mail could not parse are refused outright when they hold whitespace, control characters or angle brackets. message_id is minted as <uuid@domain-of-from> when the pin is empty and is always reported on the message_id out-pin. Suppressed in simulation: a dry-run never sends.