C# 如何在从EWS获取电子邮件时获取MimeContent？

我正在我的应用程序中使用EWS服务。此时，我想获取一封现有的电子邮件，然后将其转换为文件。我正在为此使用以下代码

private ExchangeService _service = null;

internal EWSClient()
{
     _service = new ExchangeService(ExchangeVersion.Exchange2010_SP1);
     _service.Credentials = new WebCredentials(HandlerSettings.MailReceiverLogin, HandlerSettings.MailReceiverPassword);
     _service.Url = new Uri(HandlerSettings.MailReceiverServer);
}

要获取电子邮件，我使用Bind方法

var completeEmailMessage = EmailMessage.Bind(_service, emailId);
var mimeContent = completeEmailMessage.MimeContent;
string tempFile = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString() + ".eml");
using (var fileStream = new FileStream(tempFile, FileMode.Create))
{
      fileStream.Write(mimeContent.Content, 0, mimeContent.Content.Length);
}

在这里，我得到的异常是completeEmailMessage.MimeContent；是空的

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我应该使用哪种方法来获取包含MimeContent的完整电子邮件？

您应该创建一个PropertySet并将MimeContent添加为要加载的属性，然后将其指定为Bind eg的重载属性

        PropertySet psPropSet = new PropertySet(BasePropertySet.FirstClassProperties);
        psPropSet.Add(ItemSchema.MimeContent);
        var completeEmailMessage = EmailMessage.Bind(_service, emailId, psPropSet);
        var mimeContent = completeEmailMessage.MimeContent;
        string tempFile = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString() + ".eml");
        using (var fileStream = new FileStream(tempFile, FileMode.Create))
        {
            fileStream.Write(mimeContent.Content, 0, mimeContent.Content.Length);
        }