Handle zip within zip.

test/ziploop

@@ -0,0 +1,47 @@
+From [email protected] Thu Jun 16 10:23:13 2005
+Received: from thfalcon.com (unknown [202.90.113.150])
+	by thfalcon.com (Postfix) with ESMTP id 32F0DD819C
+	for <[email protected]>; Thu, 16 Jun 2005 15:42:08 +0700 (ICT)
+From: [email protected]
+To: [email protected]
+Subject: Returned mail: see transcript for details
+Date: Thu, 16 Jun 2005 15:50:10 +0700
+MIME-Version: 1.0
+Content-Type: multipart/mixed;
+	boundary="----=_NextPart_000_0014_E4E04420.5619685C"
+X-Priority: 3
+X-MSMail-Priority: Normal
+X-Mailer: Microsoft Outlook Express 6.00.2600.0000
+X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000
+Message-Id: <[email protected]>
+Received-SPF: pass (mail.bmsi.com: guessing: domain of thfalcon.com designates 203.147.3.44 as permitted sender) client-ip=203.147.3.44; [email protected]; helo=thfalcon.com;
+
+This is a multi-part message in MIME format.
+
+------=_NextPart_000_0014_E4E04420.5619685C
+Content-Type: text/plain;
+	charset=us-ascii
+Content-Transfer-Encoding: 7bit
+
+Message could not be delivered
+
+
+------=_NextPart_000_0014_E4E04420.5619685C
+Content-Type: application/octet-stream;
+	name="[email protected]"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+	filename="[email protected]"
+
+UEsDBAoAAAAAAM6r0DL7SfbCBAEAAAQBAAAFABUAdC56aXBVVAkAA7MnskK4J7JCVXgEAIYD
+ZQBQSwMECgAAAAAANVXCMtpXacQaAAAAGgAAADMAFQB6aXAuZG9jICAgICAgICAgICAgICAg
+ICAgICAgICAgICAgICAgICAgICAgICAgIC5leGVVVAkAA6Yan0KmGp9CVXgEAIYDZQBUaGlz
+IHByb2dyYW0gd2FzIGEgdmlydXMuClBLAQIXAwoAAAAAADVVwjLaV2nEGgAAABoAAAAzAA0A
+AAAAAAEAAAC0gQAAAAB6aXAuZG9jICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg
+ICAgICAgIC5leGVVVAUAA6Yan0JVeAAAUEsFBgAAAAABAAEAbgAAAIAAAAAAAFBLAQIXAwoA
+AAAAAM6r0DL7SfbCBAEAAAQBAAAFAA0AAAAAAAAAAAC0gQAAAAB0LnppcFVUBQADsyeyQlV4
+AABQSwUGAAAAAAEAAQBAAAAAPAEAAAAA
+
+------=_NextPart_000_0014_E4E04420.5619685C--
+
+