Exchange Web Service API and 401 unauthorized exception

Question

When I try sending email using the EWS API, I get the following error: (in message.Send();)

The request failed. The remote server returne

Answer 1

Try changing this:

 exchangeService.Credentials = new WebCredentials("user@domain", "pwd", "domain");

into this:

 exchangeService.Credentials = new WebCredentials("user", "pwd", "domain");

Sometime the Login credentials depends on how Exchange/Active Directory it's configured. It could be user@domain or domain\user