Replace Existing Outlook Calendar Appointment

Question

I\'m doing some work with an icalndar appointment generation; this would allow a delegate to view an event\'s website and click on a link provided to add an appointment to their

Answer 1

It is possible to update an appointment, but not the way you did it. Here's what's important:

• METHOD should be REQUEST - a PUBLISH event will not update, it will be added again and again. REQUEST meeting requests behave differently, and will update the existing meeting even before the user approves it. I'd note that if the events are already of type Publish, they cannot be updated (at least to my knowledge).
• You must use the exact same UID.
• DTSTAMP should be bigger than the existing date stamp (this should be OK if you're creating it dynamically)
• Include an ORGANIZER - Outlook may not allow people to accept the meeting without it (not really related, but important).

I have a partial summery of this in my blog - Sending Meeting Requests to Outlook via ASP.NET Mail Message, though it's missing sending the approval to the organizer, and time zones (which are very important, so I've heard).

See also: RFC 2446 - iTIP, search for section 1.3 ITIP Roles and Transactions