Connecting to EWS by using the EWS Managed API

Instantiate the ExchangeService class.

ExchangeService service = new ExchangeService();

Note:

Instantiating ExchangeService with an empty constructor will create an instance that is bound to the latest known version of Microsoft Exchange Server. Alternatively, you can target a specific version of Exchange Server by specifying version as a parameter. ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2007_SP1); For more information about versioning in the EWS Managed API, see Versioning EWS requests.

Set the credentials of the user who sends requests to the Exchange server. If you want to connect to Exchange Web Services from a computer that is logged on to the domain, using the credentials of the authenticated user, set the UseDefaultCredentials property on the ExchangeService object to true.

// Connect by using the default credentials of the authenticated user.
service.UseDefaultCredentials = true;

If you do not want to connect by using the default user credentials, set the Credentials property on the ExchangeService object to explicitly specify the credentials of a different user.

// Connect by using the credentials of user1 at contoso.com.
service.Credentials = new WebCredentials("user1@contoso.com", "password");

You can also specify the credentials of the user by using the user's domain name and password.

// Connect by using the credentials of contoso/user1.
service.Credentials = new WebCredentials(“user1”, “password”, “contoso”);

Note:
If the UseDefaultCredentials property is set to true, the value of the Credentials property is ignored.

Set the URL of the Exchange Web Services endpoint. This URL locates the exchange.asmx file on the Exchange server that has the Client Access server role installed.

// Use Autodiscover to set the URL endpoint.
service.AutodiscoverUrl("user1@contoso.com");

Note:

Although you can explicitly set the Url property of the ExchangeService to a hardcoded value, using the Autodiscover service instead is recommended for the following reasons: Autodiscover determines the best endpoint for a given user (the endpoint that is closest to the user's Mailbox server). The Exchange Web Services URL might change if new Client Access servers are deployed. In this scenario, using Autodiscover means no code changes are necessary. You should either set the URL explicitly or call AutodiscoverUrl, but you should not do both. For more information about Autodiscover, see Working with the Autodiscover service by using the EWS Managed API.