_Really_ disable reminder via ics in Outlook

I've designed a web interface to send all day events to Outlook 2007 calendars. This is done by sending a mail with content-type "text/calendar" and adding an ics Text as AlternateView (Calendar).

This works fine except for one flaw: There 开发者_开发技巧should occur no reminder. According to ics-Standard this is done by simply dropping the "VALARM" part. But the behaviour of Outlook is different. If i drop that part, it adds the "Default Reminder" Setting in the recipients' Outlook. The result is that one recipient has a 30 minutes reminder, the other a 15 minutes reminder, and others have no reminder - according to their "default reminder" settings.

I've searched a lot to find a way to force reminder to none but I couldn't find any hint whatsoever.

I hope you can help me with this.

Thanks, ro28

Microsoft's spec says this is not possible (page 83 of MS-OXCICAL pdf):

If no such TRIGGER property could be parsed, PidLidReminderDelta SHOULD<265> be set to 0x0000000F for non-all day appointments and 0x00000438 for all day appointments.

<265> Section 2.1.3.1.1.20.62: In this case, Exchange 2003, Exchange 2007, Exchange 2010, Exchange 2013, and Exchange 2016 set PidLidReminderDelta to 0x0000000F for all Calendar objects.