| Content-Type: multipart/mixed; boundary="AAA" | |
| From: Mail Delivery Subsystem <xxx@example.com> | |
| To: yyy@example.com | |
| This is a MIME-encapsulated message | |
| --AAA | |
| Stuff | |
| --AAA | |
| Content-Type: message/rfc822 | |
| From: webmaster@python.org | |
| To: zzz@example.com | |
| Content-Type: multipart/mixed; boundary="BBB" | |
| --BBB-- | |
| --AAA-- |