I recently had an opportunity to work with Exchange server having created an ExtJs/Ext.Net based email client for Exchange. And I used the Exchange Web Services Managed API for .NET to interface with the Exchange server itself.

One of the aspects of the email client was downloading email attachments. I could not find anything on web that explained downloading attachments through the EWS Managed API (though there are examples for other interfaces used to interact with Exchange). And the MSDN documentation for the API is still not as mature as other MSDN documentation (without a surprise as the API itself is under development).

So, after having played around a little, I found my way out for downloading the attachments.

You need to know the EmailMessage UniqueId as well as the desired Attachment’s Id to open a System.IO.Stream containing the contents of the attachment. And then you can do anything with this Stream, like saving it as a file on the server, or sending its contents to the client.

Here’s the interesting part of the code for the same. The code opens (loads) an attachment whose Email UniqueId and Attachment Id are known (through a previous call to the Exchange probably), and then sends the Attachment content to a http client for downloading:


{syntaxhighlighter brush: csharp;fontsize: 100; first-line: 1; }//Instantize a new ExchangeService instance with the desired parameters here.
ExchangeService service=context.getExchangeService();

//Bind to the email message with known id.
EmailMessage m=EmailMessage.Bind(service, new ItemId(mailId), new PropertySet(EmailMessageSchema.Attachments));

//Figure out the desired attachment.
FileAttachment a=null;
foreach (Attachment at in m.Attachments)
if (at.Id.Equals(attachmentId))
a = (FileAttachment) at;

//Load the attachment in memory from Exchange.
MemoryStream stream=new MemoryStream();
StreamReader reader=new StreamReader(stream);
stream.Seek(0, SeekOrigin.Begin);

//Send the attachment to client.
HttpResponse response=context.Response;
response.Charset = “”;
response.ContentType = type;
response.AddHeader(“Content-Disposition”, “attachment; filename=” + name);

response.CacheControl = “private”;
response.AddHeader(“Pragma”, “no-cache”);


catch (Exception) { }{/syntaxhighlighter}

This is mostly boilerplate code that you can easily move to a generic .ashx handler to be able to download attachments.

One such handler is attached with this post that expects the EmailMessage UniqueId, Attachment Id, Attachment Mime Type and Name as request parameters and send the desired attachment to the client for downloading.