Incoming E-Mail to SP Calendar: Value cannot be null.

Hey everyone,

for some time now (I'm afraid I cannot recall since when), the following problem appears with our SharePoint 2010 Server instance. (It did work for some time after I had set it up for the first time, but at some point stopped working without changing anything regarding the configuration or infrastructure):

In one of the SharePoint sites, I have a list of the Calendar type
I configured and set up incoming e-mail support, so users could add the SP calendar to their Outlook 2010 appointments, which would send an invitation mail, which then added the appointment in the SP calendar
As I said: This worked fine for quite a while, but then stopped working. The mails are perfectly delivered to the Mailroot\Drop dir by the SMTP service, and they are picked up and deleted by the Incoming E-Mail SharePoint Timer Job.

Whenever an e-mail is in the Drop dir, the job obviously tries to parse it and gives the following error message:

An error occurred while processing the incoming e-mail file C:\Inetpub\mailroot\Drop\86d3c93401cab0ba0000002b.eml. The error was: Value cannot be null.  Parameter name: stream.    

I googled the problem and some folks said this was due to Exchange settings regarding the content type (Rich Text vs. Plain Text, as far as I understand). But: We don't use Exchange. SharePoint yes, but another mail server software.

I also tried changing the contact in my Outlook 2010 address book so that it would only send plain text messages to the calendar's address - no success.

I found this thread:

https://social.technet.microsoft.com/Forums/office/en-US/3de28156-b62d-455d-810c-c52ff9cde7ef/wss-30-sp2-calendar-incoming-email-problem?forum=sharepointadminlegacy

So my clue was that SharePoint could only handle invites which are of Content-dis, and maybe the base64 encoding is also a factor - but that's just my assumption. Sadly, the thread's solution does not apply to my environment.

Here is an .eml file from the maildrop dir which results in the aforementioned error message:

x-sender: n****.r*****@f******.de
x-receiver: ffccalendar@s****l.f****mail.de
Received: from f****il.de ([***.***.***.***]) by s****l.f****mail.de with Microsoft SMTPSVC(7.5.7601.17514);
	 Wed, 11 Mar 2015 18:22:27 +0100
Date: Wed, 11 Mar 2015 18:22:15 +0100
X-Footer: Zm9yZXN0ZmluYW5jZS5kZQ==
Received: from localhost ([127.0.0.1])
	by f****mail.de (Kerio Connect 8.4.1)
	for ffccalendar@s****l.f****mail.de;
	Wed, 11 Mar 2015 18:22:13 +0100
Subject: test
Importance: Normal
X-Priority: 3
Message-ID: <fe93afad-fb40-4541-8014-e542761fa655@f*********.de>
From: N***** R***** <n****.r*****@f******.de>
To: FFC Calendar <ffccalendar@s****l.f****mail.de>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="=-zc0DDwzDqdjmB0kgoz7A"
Return-Path: n****.r*****@f******.de
X-OriginalArrivalTime: 11 Mar 2015 17:22:27.0659 (UTC) FILETIME=[F28999B0:01D05C1F]

--=-zc0DDwzDqdjmB0kgoz7A
Content-Type: text/plain; charset="utf-8"

Subject: test
Location: test
When: 2015-03-12, 09:30 - 10:00 GMT +1:00 (30 minutes)
Organizer: N****** R*****
(n****.r*****@f******.de)
Required Attendees: FFC Calendar (ffccalendar@s****l.f****mail.de)


--=-zc0DDwzDqdjmB0kgoz7A
Content-Type: text/html; charset="utf-8"<table style='font: 12px Verdana, Arial, sans-serif'><tr><td><b>Subject: </b></td><td>test</td></tr><tr><td><b>Location: </b></td><td>test</td></tr><tr><td><b>When: </b></td><td>2015-03-12, 09:30 - 10:00 GMT +1:00 (30 minutes)</td></tr><tr><td><b>Organizer: </b></td><td>N****** R***** (<a href="mailto:n****.r*****@f******.de">n****.r*****@f******.de</a>)</td></tr><tr><td><b>Required Attendees: </b></td><td>FFC Calendar (ffccalendar@s****l.f****mail.de) (<a href="mailto:ffccalendar@s****l.f****mail.de">ffccalendar@s****l.f****mail.de</a>)</td></tr></table><p style='font: 12px Verdana, Arial, sans-serif'>
--=-zc0DDwzDqdjmB0kgoz7A
Content-class: urn:content-classes:calendarmessage
Content-Type: text/calendar;
	charset="utf-8";
	component="vevent";
	method="request";
	name="meeting.ics"

BEGIN:VCALENDAR
PRODID:-//Kerio Technologies//Outlook Connector//EN
METHOD:REQUEST
VERSION:2.0
X-VERSION-KMS:6.2.0
BEGIN:VTIMEZONE
TZID:Amsterdam, Belgrade, Berlin, Brussels, Budapest, Madrid,
  Paris, Prague, Stockholm
BEGIN:STANDARD
DTSTART:19961027T030000
TZOFFSETTO:+0100
TZOFFSETFROM:+0200
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19810329T020000
TZOFFSETTO:+0200
TZOFFSETFROM:+0100
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
DTSTAMP:20150311T172224Z
UID:80462778A326E04EBD831336D01F2A2FB99329322DC5774A858BF3A4
 F9D1D9B2040000008200E00074C5B7101A82E00800000000004F205E275CD001000000000000
 000010000000
PRIORITY:5
SUMMARY:test
TRANSP:OPAQUE
X-MICROSOFT-CDO-BUSYSTATUS:TENTATIVE
LOCATION:test
X-LABEL:0
X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
CLASS:PUBLIC
SEQUENCE:2
ORGANIZER;CN="N***** R******":mailto:n****.r*****@f******.de
ATTENDEE;RSVP=TRUE;X-SENT=TRUE;CN="FFC Calendar (ffccalendar@s****l.f****mail.de)";CUTYPE=INDIVIDUAL:mailto:ffccalendar@s****l.f****mail.de
X-ALARM-TRIGGER:-PT15M
DTSTART;TZID="Amsterdam, Belgrade, Berlin, Brussels, Budapest, Madrid, Paris, Prague, Stockholm":20150312T093000
DTEND;TZID="Amsterdam, Belgrade, Berlin, Brussels, Budapest, Madrid, Paris, Prague, Stockholm":20150312T100000
BEGIN:VALARM
ACTION:DISPLAY
DESCRIPTION:test
TRIGGER;RELATED=START:-PT15M
END:VALARM
END:VEVENT
END:VCALENDAR

--=-zc0DDwzDqdjmB0kgoz7A--

Furthermore, I tried sending an invitation with a totally different account using Thunderbird/Lightning, resulting in this .eml file, same error:

x-sender: n***@t*****l.de
x-receiver: ffccalendar@s****l.f****mail.de
Received: from f****mail.de ([***.***.***.***]) by s****l.f****mail.de with Microsoft SMTPSVC(7.5.7601.17514);
	 Wed, 11 Mar 2015 19:00:44 +0100
Message-ID: <167690368-17108@f****mail.de>
X-Spam-Status: No, hits=0.0 required=4.5
	tests=BAYES_00: -1.665,MISSING_MID: 0.497,TVD_SPACE_RATIO: 0.001,
	TOTAL_SCORE: -1.167,autolearn=no
X-Spam-Level:
Received: from t*****l.de ([***.***.***.***])
	by f****mail.de (Kerio Connect 8.4.1)
	for ffccalendar@s****l.f****mail.de;
	Wed, 11 Mar 2015 19:00:23 +0100
Received: from [***.***.***.***] (p57A56D02.dip0.t-ipconnect.de [87.165.109.2])
	(using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))
	(No client certificate requested)
	by t******l.de (Postfix) with ESMTPSA id 7CDC918552F
	for <ffccalendar@s****l.f****mail.de>; Wed, 11 Mar 2015 19:00:34 +0100 (CET)
MIME-version: 1.0
From: n***@t*****l.de
To: ffccalendar@s****l.f****mail.de
Date: Wed, 11 Mar 2015 18:00:33 GMT
Subject: Event Invitation: Test
Content-class: urn:content-classes:calendarmessage
Content-Type: text/calendar;
	charset="UTF-8";
	method="REQUEST";
	component="VEVENT";
	name="meeting.ics"
Content-transfer-encoding: 8BIT
Return-Path: n***@t*****l.de
X-OriginalArrivalTime: 11 Mar 2015 18:00:44.0911 (UTC) FILETIME=[4BCE6FF0:01D05C25]

BEGIN:VCALENDAR
PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN
VERSION:2.0
METHOD:REQUEST
BEGIN:VTIMEZONE
TZID:Europe/Berlin
X-LIC-LOCATION:Europe/Berlin
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:19700329T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:19701025T030000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
CREATED:20150311T175958Z
LAST-MODIFIED:20150311T180029Z
DTSTAMP:20150311T180029Z
UID:02970c76-15bd-428f-ac00-78617abb16f3
SUMMARY:Test
ORGANIZER;RSVP=TRUE;CN=N***** R*****;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:
 n***@t*****l.de
ATTENDEE;RSVP=TRUE;PARTSTAT=NEEDS-ACTION;ROLE=REQ-PARTICIPANT:mailto:ffcca
 lendar@s****l.f***mail.de
DTSTART;TZID=Europe/Berlin:20150312T070000
DTEND;TZID=Europe/Berlin:20150312T080000
TRANSP:OPAQUE
END:VEVENT
END:VCALENDAR

I also tried to activate the highest loglevel for the "E-Mail" category, but still only that one error message in the ULS log.

So I don't even have any clue, _which_ part of the mail cannot be parsed.

On another thread, I read that the same problem happened to another user after the SharePoint 2010 SP2 upgrade. This might be the case for my environment, too, but I cannot recall it exactly.

So has anyone a clue where to look further, or perhaps even a solution?

Kind regards
Nico