Exchange 2010, find out if email is meeting invite without loading attachment

Question

I have a mail sniffer program running on an Inbox in Exchange Server 2010 that checks emails at certain intervals. I would like to know if it somehow is possible to programmatically check with EWS (Exchange Web Services) if an email (EmailMessage) is a meeting invite (calendar request) without loading the attachment.

I know I can check if an attachment is an Microsoft.Exchange.WebServices.Data.ItemAttachment and then, after loading the email check if this is an Microsoft.Exchange.WebServices.Data.Appointment. But this only checks if the attachment is an invite. Theoretically someone could forward an email with amongst other thing an email invite. Then the email is really not a meeting invite, just a forwarded email.

Can you know if an email is a meeting invite without loading the attachment? Should this not be possible with EWS, is there an authorative source for this?

Edit: Forwarded emails

This is outside the question, but I originally asked:

Alternatively (but not what I am hoping for), is there a way to know if an email was forwarded so that I can handle them differently?

This has been answered here. But I still would like to get an answer for my question as this answer only helps creating a workaround for some cases.

Thanks in advance!

Answer 1

You can leverage the EmailMessage Message Class ItemSchema.ItemClass property to determine what type an item is. Here is a snippet to help you out...

 FindItemsResults<Item> mailItems = inbox.FindItems(new ItemView(1000) { PropertySet = new PropertySet(ItemSchema.Id, ItemSchema.HasAttachments, ItemSchema.Subject, ItemSchema.ItemClass) }); 
 foreach (EmailMessage message in messageItems)
 {    
   if (message.ItemClass == "IPM.Schedule.Meeting.Request")
     // we have a meeting request
 }