使用EWS托管api转发电子邮件,保留标头

using Microsoft.Exchange.WebServices.Data;

// 连接到Exchange服务器
ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2013);
service.Credentials = new WebCredentials("username", "password");
service.Url = new Uri("https://outlook.office365.com/EWS/Exchange.asmx");

// 获取原始邮件
EmailMessage originalMessage = EmailMessage.Bind(service, new ItemId("messageId"));

// 创建新邮件
EmailMessage forwardedMessage = new EmailMessage(service);
forwardedMessage.Subject = "FW: " + originalMessage.Subject;
forwardedMessage.Body = new MessageBody(originalMessage.Body.Text);
forwardedMessage.ToRecipients.AddRange(originalMessage.ToRecipients);

// 复制原始邮件的标头信息
foreach (InternetHeader header in originalMessage.InternetMessageHeaders)
{
    forwardedMessage.InternetMessageHeaders.Add(header);
}

// 发送新邮件
forwardedMessage.Send();

// 标记原始邮件为已读，并将其移动到另一个文件夹中
originalMessage.SetExtendedProperty(new ExtendedPropertyDefinition(DefaultExtendedPropertySet.InternetHeaders, "X-Forwarded-To", MapiPropertyType.String), "forwarded@example.com");
originalMessage.Move(WellKnownFolderName.Inbox);