服务帐户中的 Exchange 模拟：无法找到自动发现服务

通过 ews 发送简单的电子邮件正在按预期工作 - 从我的帐户到我的帐户：

ExchangeService ews = new ExchangeService(ExchangeVersion.Exchange2010);
ews.AutodiscoverUrl("[email protected]");
EmailMessage email = new EmailMessage(ews);
email.ToRecipients.Add("[email protected]");
email.Subject = "HelloWorld";
email.Body = new MessageBody("This is the first email I've sent by using the EWS Managed API");
email.Send();

只需尝试模拟，它也按预期工作 - 在最后一行，它返回不允许我模拟的错误：

ExchangeService ews = new ExchangeService(ExchangeVersion.Exchange2010);
ews.AutodiscoverUrl("[email protected]");
ews.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, "[email protected]");
EmailMessage email = new EmailMessage(ews);
email.ToRecipients.Add("[email protected]");
email.Subject = "HelloWorld";
email.Body = new MessageBody("This is the first email I've sent by using the EWS Managed API");
email.Send();

现在我尝试使用我的应用程序服务帐户登录：

ExchangeService ews = new ExchangeService(ExchangeVersion.Exchange2010);
ews.Credentials = new NetworkCredential("service", "1234", "mydomain.com");
//ews.Credentials = new WebCredentials("service", "1234");
ews.AutodiscoverUrl("[email protected]");
//ews.AutodiscoverUrl("[email protected]");
ews.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, "[email protected]");
EmailMessage email = new EmailMessage(ews);
email.ToRecipients.Add("[email protected]");
email.Subject = "HelloWorld";
email.Body = new MessageBody("This is the first email I've sent by using the EWS Managed API");
email.Send();

但这里它在自动发现行中抛出错误：“AutodiscoverLocalException：无法找到自动发现服务。”

服务帐户已在 AD 和 Exchange 中设置，并具有正确的密码和 smtp 地址。

为什么它不起作用？我如何检查导致该错误的原因？

我解决了问题，猜猜问题是什么：是用户帐户。

EWS 使用给定的凭据对自身进行身份验证，以便访问自动发现服务：

http://mydomain/AutoDiscover/AutoDiscover.xml

凭据是正确的，但似乎对于设置为“用户必须在首次登录时更改密码”的帐户，对自动发现服务的访问被拒绝。我在 AD 中更改了该设置，现在它可以工作了。