In troubleshooting an issue for a customer, I ran into a problem: I could obtain the data from the MAPI store (via EWS) but I was unable to figure out how to cast from the list of items obtained to an actual message to action against.
For example, here's where I was attempting to obtain the items from the MAPI container:
Console.WriteLine("Connecting to EWS endpoint...");
ExchangeService ExService = newExchangeService(ExchangeVersion.Exchange2007_SP1);
ExService.Credentials = new WebCredentials(targetMBX, passWord);
// Obtain the message to reply to.
ItemView iv = new ItemView(3);
FindItemsResults<Item> zeitem = ExService.FindItems(WellKnownFolderName.Inbox, iv);
As you can see, we're calling FindItems and returning it as a collection of Items. I thought a cast would have to occur, to convert the Item back into an EmailMessage. Instead, as one would be happy to find out as I was, the Item is an encapsulation of the EmailMessage and we can 'extract' it via an array call:
var item = zeitem.Items;
From this, we can further action against the mail items via EWS:
if (item is EmailMessage)
Console.WriteLine("Working with the first item found.");
// Reply to the message
ResponseMessage responseMessage = message.CreateReply(replyToAll);
string myReply = "This is a test of the EWS responseMessage method[s].";
responseMessage.BodyPrefix = myReply;
var messageToSend = responseMessage.Save();
// Send and save a copy of the replied email message in the default Sent Items folder.
Using the EWS API, one can do many powerful and important administrative tasks in Exchange. You can read more about it, here.