ICS in Outlook is sent as a .msg file

Question

I have an application, it creates ICS similar to the following:

BEGIN:VCALENDAR VERSION:2.0 METHOD:REQUEST BEGIN:VEVENT ATTENDEE;ROLE=REQ-PARTICIPANT;RSVP=TRUE:MAILTO:[e-mail] ORGANIZER:MAILTO:[e-mail] DTSTART:20100803T190000Z DTEND:20100803T200000Z LOCATION:Go to http://100.200.0.55/Login/ParticipantLogIn.asp and enter Conference ID: 0000 SEQUENCE:0 UID:352C75A6-0117-4B3A-AFE6-7B18649CD45A DTSTAMP:20100803T184455Z DESCRIPTION:TO ACCESS THE WEB CONFERENCE:\n\n Click on the link bel ow:\n SUMMARY:Test User Conference PRIORITY:5 CLASS:PUBLIC BEGIN:VALARM TRIGGER:-PT15M ACTION:DISPLAY DESCRIPTION:Reminder END:VALARM END:VEVENT END:VCALENDAR 

When sent to a Gmail account, it is sent as an ICS file, and everything is correct. When sent to Outlook 2003 or 2007, it is attached as a .msg file and is binary. The server used is Windows Server 2008. I set the mime ics type as text / calendar on it. The process of adding it is simply to create a tmp file on disk and add it as an attachment, and then send it using CDO. Does anyone know why Outlook will add it as .msg?

In addition, we use the same exchange server, and it works great with Windows Server 2003.

Update using network trace for attachment

2003

 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.4073 Content-Type: application/octet-stream; name="meeting.ics" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="meeting.ics" 

2008

 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18197 Content-Type: text/calendar; name="meeting.ics" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="meeting.ics" 

There are four parts to the message in both parts:

• Text
• HTML
• Appendix 1
• Appendix 2

In version 2003, which works, one is the application / octet stream, and one is calendar / text. In 2008, both of them - calendar / text.

Answer 1

Are you adding VCALENDAR as the main (and only) part of MIME or as one of the attachments? There is a big difference.

Answer 2

This looks like a problem with CDO on Windows Server 2008. Tracing the network traffic on each server showed a huge difference in the transmitted message.

It seems that for some reason, the AddAttachment method does not use the same MIME as in 2003. Manually adding an attachment and managing MIME will fix it.

Answer 3

TNEF data may not be in the letter. If so, the email will be displayed as plain text. You should check the TNEF settings to see if these creatures are missing from the letters.

Check the ESM to see if the TNEF removal option is enabled.

From MSDN:

In addition to the receiving client, it is not uncommon for a mail server to retrieve TNEF information from as it is delivered. If the server option for removing TNEF is enabled, clients will always receive a text version of the message. Microsoft Exchange Server is an example mail server application that has the ability to remove TNEF from messages.