EHLO example.com MAIL FROM: RCPT TO: DATA Subject: Your Subject From: sender@example.com To: recipient@example.com MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="boundary-string" --boundary-string Content-Type: multipart/alternative; boundary="alternative-boundary" --alternative-boundary Content-Type: text/plain This is the plaintext part of the email. --alternative-boundary Content-Type: text/html


This is the HTML part of the email.

--alternative-boundary-- --boundary-string Content-Type: image/svg+xml Content-Id: Content-Disposition: attachment; filename="42.svg" 42 --boundary-string-- . QUIT