What's wrong with UserDefaultCredentials

Question

Hello stackoverflowers!

I'm using Exchange Web Service exposed from exchange 2007 SP1 server to create emails from my application and I've encounted a problem I can't figure out.

I get this response "When making a request as an account that does not have a mailbox, you must specify the mailbox primary SMTP address for any distinguished folder Ids." everytime I try to CreateItem() from a web application.

This only happens on a Windows 2003 + IIS6 when UseDefaultCredentials = True. But it's fine if I set the credentials with New System.Net.NetworkCredential("user","password"). The latter is not an option in production.

The strangest thing is that UseDefaultCredentials = True works if I run it from VS2008 on my local machine (but the exchange server is the same remote machine). What is wrong?

To make this more readable I've pasted a code example that uses Exchange WS API 1.0 here below. But it's the same problem if I use the Exchange WS directly.

    Dim serviceObj As ExchangeService = _
        New ExchangeService(ExchangeVersion.Exchange2007_SP1)
    serviceObj.UseDefaultCredentials = True
    serviceObj.Url = New Uri(serviceUrl)
    Dim message = New EmailMessage(serviceObj)
    message.Subject = "Greetings"
    message.Body = New MessageBody(BodyType.Text, "Hello World")
    message.ToRecipients.Add("[email protected]")
    message.SendAndSaveCopy()

Thankful for any thoughts.

Answer 1

defaultCredentials="false" shoud be false

and you can put this email Settings in web.config

<system.net>
 <mailSettings>
  <smtp deliveryMethod="Network">
   <network defaultCredentials="false" port="25" host="mail.domain.com" userName="[email protected]" password="123"/>
  </smtp>
 </mailSettings>
</system.net>

Answer 2

Is this a desktop app or a web app? If it's the latter perhaps DefaultCredentials is using the app pool identity?

What happens if you use:

System.Net.CredentialCache.DefaultCredentials

And UseDefaultCredentials as false?

Answer 3

The problem was solved by using Impersonation.