Exchange Server 2013 EMail驱动程序

我有一个c#程序连接到我的Exchange Server 2010，能够阅读每一封电子邮件。

我正在使用microsoft.exchange.webservices.dll库。

问题是，这个程序在Exchange Server 2013上返回以下异常:"The remote server returned an error: (501) Not Implemented."

我不知道这两个服务器有什么不同。

编辑:一些代码片段:

ExchangeVersion version = ExchangeVersion.Exchange2013; ExchangeService service = new ExchangeService(version); service.Credentials = new NetworkCredential("user", "pw", "domain"); service.AutodiscoverUrl("emailaddr");

，这里出现了异常:

SearchFilter sf = new SearchFilter.SearchFilterCollection(LogicalOperator.And, new SearchFilter.IsEqualTo(EmailMessageSchema.IsRead, false));

FindItemsResults<Item> findResults = service.FindItems(WellKnownFolderName.Inbox, sf, new ItemView(20));

service.LoadPropertiesForItems(findResults.Items, PropertySet.FirstClassProperties);

string mailsender = item.LastModifiedName;