From: alice@example.com
To: bob@example.com
Cc: carol@example.com
Bcc: dave@example.com
Subject: Example Multipart Digest Email
Message-ID: <1234567890@example.com>
MIME-Version: 1.0
Content-Type: multipart/digest; boundary="boundary123"

--boundary123
Content-Type: message/rfc822

From: eve@example.com
To: alice@example.com
Subject: First Message

This is the first message in the digest.

--boundary123
Content-Type: message/rfc822

From: frank@example.com
To: bob@example.com
Subject: Second Message

This is the second message in the digest.

--boundary123
Content-Type: message/rfc822

From: grace@example.com
To: carol@example.com
Subject: Third Message

This is the third message in the digest.

--boundary123--