I am running into a very strange issue and I am convinced it is just something stupid that I am overlooking. Using the EWS managed API, I try to connect to a mailbox to read the contacts. Originally, I used the default credentials, in which case the auto discovery worked. The problem is that later on we want to run this on a server and impersonate a user, so I changed it by manually specifying the credentials. This then broke, even when using my own credentials.
As an example, this worked:
service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
service.AutodiscoverUrl("user@example.com", redirect => true);
This did not:
service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
service.UseDefaultCredentials = false;
service.Credentials = new NetworkCredential("user", "pass", "EXAMPLE_DOMAIN");
service.AutodiscoverUrl("user@example.com", redirect => true);
The given network credentials should be exactly the same as the default credentials, but when enabling the tracing, I get the response "401 Unauthorized" in the second case, so it is not acting as if it is the same.
What am I missing?