Merge pull request #150 from 0xcdcdcdcd/patch-1

ビルドテストは落ちてるけど、メールファイル単体の追加なので一旦取り込んでから修正してみる。
https://travis-ci.org/azumakuniyuki/p5-Sisimai/builds/98663768

eg/cannot-parse-yet/no-message-id.txt

@@ -0,0 +1,75 @@
+Return-Path: <>
+X-Original-To: bounce@sample.net
+Delivered-To: bounce@sample.net
+Received: by sample.net (Postfix)
+	id 5CCF31FF869; Tue, 22 Dec 2015 19:03:54 +0900 (JST)
+Date: Tue, 22 Dec 2015 19:03:54 +0900 (JST)
+From: MAILER-DAEMON@sample.net (Mail Delivery System)
+Subject: Undelivered Mail Returned to Sender
+To: bounce@sample.net
+Auto-Submitted: auto-replied
+MIME-Version: 1.0
+Content-Type: multipart/report; report-type=delivery-status;
+	boundary="7B63E1FF867.1450778634/sample.net"
+Message-Id: <20151222100354.5CCF31FF869@sample.net>
+
+This is a MIME-encapsulated message.
+
+--7B63E1FF867.1450778634/sample.net
+Content-Description: Notification
+Content-Type: text/plain; charset=us-ascii
+
+This is the mail system at host sample.net.
+
+I'm sorry to have to inform you that your message could not
+be delivered to one or more recipients. It's attached below.
+
+For further assistance, please send mail to postmaster.
+
+If you do so, please include this problem report. You can
+delete your own text from the attached returned message.
+
+                   The mail system
+
+<nobody@sample.co.jp>: host smtp.sample.co.jp[100.100.100.100] said: 550
+    5.1.1 <nobody@sample.co.jp>: Recipient address rejected: User unknown
+    in virtual mailbox table (in reply to RCPT TO command)
+
+--7B63E1FF867.1450778634/sample.net
+Content-Description: Delivery report
+Content-Type: message/delivery-status
+
+Reporting-MTA: dns; sample.net
+X-Postfix-Queue-ID: 7B63E1FF867
+X-Postfix-Sender: rfc822; bounce@sample.net
+Arrival-Date: Tue, 22 Dec 2015 19:03:53 +0900 (JST)
+
+Final-Recipient: rfc822; nobody@sample.co.jp
+Original-Recipient: rfc822;nobody@sample.co.jp
+Action: failed
+Status: 5.1.1
+Remote-MTA: dns; smtp.sample.co.jp
+Diagnostic-Code: smtp; 550 5.1.1 <nobody@sample.co.jp>: Recipient address
+    rejected: User unknown in virtual mailbox table
+
+--7B63E1FF867.1450778634/sample.net
+Content-Description: Undelivered Message
+Content-Type: message/rfc822
+
+Return-Path: <bounce@sample.net>
+Received: from sample.net (localhost [127.0.0.1])
+	by sample.net (Postfix) with ESMTP id 7B63E1FF867
+	for <nobody@sample.co.jp>; Tue, 22 Dec 2015 19:03:53 +0900 (JST)
+Content-Type: text/plain; charset=utf-8
+From: <no-reply@sample.net>
+To: nobody@sample.co.jp
+Subject: Test
+Date: Tue, 22 Dec 2015 19:03:53 +0900
+Content-Transfer-Encoding: quoted-printable
+Message-Id: 
+ <1450778633482-7a300d1b-b56ac3ba-1129eeae@sample.net>
+MIME-Version: 1.0
+
+This is test mail.
+
+--7B63E1FF867.1450778634/sample.net--