Glen's Exchange and Office 365 Dev Blog

Sender Flags are an Outlook Feature that allow you to set a follow up flag on Message when your sending it as well as being able to set a Recipient Followup flag if you want to. (eg) What happens in Exchange when you set a Sender Flag on a Message is documented in the Informational Flagging Protocol document  http://msdn.microsoft.com/en-us/library/cc433487(v=exchg.80).aspx  . If you want to do the same thing to a Message your sending in EWS there is nothing in the strongly typed classes to help out so you need to manually set two of the extended properties that are documented in that protocol document before you send the message and the Store will do the rest on submit. (More specifically what happens with the properties involved is documented here  http://msdn.microsoft.com/en-us/library/ee217246(v=exchg.80).aspx  ) The important properties that are involved with sender flags are the PidTagSwappedToDoData which is used to Store the information...