1Content-Type: multipart/mixed; boundary="AAA" 2From: Mail Delivery Subsystem <xxx@example.com> 3To: yyy@example.com 4 5This is a MIME-encapsulated message 6 7--AAA 8 9Stuff 10 11--AAA 12Content-Type: message/rfc822 13 14From: webmaster@python.org 15To: zzz@example.com 16Content-Type: multipart/mixed; boundary="BBB" 17 18--BBB-- 19 20--AAA-- 21