Hi,

I'm trying to develop an Outlook Add-in in C# that intercepts outgoing
emails with the "ApplicationEvents_11_ItemSendEventHandler" and modifies the
message. The Add-in should also change the "Content-Type" header of the
message.

It seems like the "MailItem" interface does not expose properties to
manipulate the "Content-Type" header, and I suspect the headers are not set
yet when the ItemSend event is fired, but does someone know any other way to
achieve this?

Thanks in advance!