通过WebDav方法读取EXCHANGE邮件的方法

/// <summary>
/// 取得未读邮件信息
/// </summary>
/// <returns></returns>
        private string GetUnReadMailList(string strUserID, string strPassword)
...{
string url = System.Configuration.ConfigurationManager.AppSettings["ExchangeServer"];
System.Net.HttpWebRequest Request;
System.Net.WebResponse Response;
System.Net.CredentialCache MyCredentialCache;
string strRootURI = url + "/" + strUserID + "/收件箱";
string strUserName = strUserID;
//string strDomain = ConfigurationSettings.AppSettings["ExchangeDomain"];
            string strDomain = System.Configuration.ConfigurationManager.AppSettings["Domain"];
string strQuery = "";
byte[] bytes = null;
System.IO.Stream RequestStream = null;
System.IO.Stream ResponseStream = null;
XmlDocument ResponseXmlDoc = null;
Epower.DevBase.Organization.SqlDAL.UserEntity user = new Epower.DevBase.Organization.SqlDAL.UserEntity(strUserID);
string strEmailXml = "";
try
...{
strQuery = "<?xml version="1.0"?><D:searchrequest xmlns:D = "DAV:" >"
+ "<D:sql>SELECT "DAV:displayname","urn:schemas:mailheader:subject","
//  + ""urn:schemas:mailheader:approved ","
//   + ""urn:schemas:mailheader:comment ","
                          + ""urn:schemas:mailheader:from","
+ ""urn:schemas:mailheader:date" FROM "" + strRootURI + """
+ "where "urn:schemas:httpmail:read"=false"
//    + "WHERE "DAV:ishidden" = false AND "DAV:isfolder" = false"
                 + "</D:sql></D:searchrequest>";
//集成验证方式下代码
                Request = (System.Net.HttpWebRequest)HttpWebRequest.Create(strRootURI);
Request.Timeout = 300000;   //超时 5分钟
                MyCredentialCache = new System.Net.CredentialCache();
MyCredentialCache.Add(new System.Uri(strRootURI),
"NTLM",
new System.Net.NetworkCredential(strUserName, user.Password, strDomain)//
                 );//NTLM集成windows验证  Basic 基本验证
                Request.Credentials = MyCredentialCache;
//Request.Credentials = CredentialCache.DefaultNetworkCredentials;
// Specify the method.
                Request.Method = "SEARCH";
// Encode the body using UTF-8.
                bytes = Encoding.UTF8.GetBytes((string)strQuery);
// Set the content header length..  This must be
// done before writing data to the request stream.
                Request.ContentLength = bytes.Length;
// Get a reference to the request stream.
                RequestStream = Request.GetRequestStream();
// Write the SQL query to the request stream.
                RequestStream.Write(bytes, 0, bytes.Length);
// Close the Stream object to release the connection
// for further use.
                RequestStream.Close();
// Set the content type header.
                Request.ContentType = "text/xml;charset="utf-8"";
// Send the SEARCH method request and get the
// response from the server.
                Response = (HttpWebResponse)Request.GetResponse();
// Get the XML response stream.
                ResponseStream = Response.GetResponseStream();
// Create the XmlDocument object from the XML response stream.
                ResponseXmlDoc = new XmlDocument();
ResponseXmlDoc.Load(ResponseStream);
strEmailXml = ResponseXmlDoc.InnerXml;
ResponseStream.Close();
Response.Close();
}
catch (Exception e)
...{
// Catch any exceptions. Any error codes from the SEARCH
// method request on the server will be caught here, also.
                return "";
}
return strEmailXml;
}