Exchange服务器阻止嵌入图像的电子邮件

Question

不幸的是，由于我们的Exchange服务提供商进行了更新，我们无法再发送带有嵌入式图像的电子邮件。

一旦我们发送电子邮件，我们就会收到此错误：“远程服务器返回错误：（401）未经授权。”如果我们从电子邮件中删除图像，一切正常。有没有解决这个问题的工作？

我们的c＃代码：

AlternateView htmlView = AlternateView.CreateAlternateViewFromString(Body, null, "text/html");
LinkedResource imagelink;
MatchCollection matches = Regex.Matches(Body, "<img.*?src=\"cid:(.*?)\"");
foreach (Match match in matches)
{
    myHttpWebRequest = (HttpWebRequest)WebRequest.Create(new Uri(match.Groups[1].Value));

    myHttpWebRequest.UseDefaultCredentials = true;
    myHttpWebRequest.PreAuthenticate = true;
    myHttpWebRequest.Credentials = CredentialCache.DefaultCredentials;

    using (myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse())
    {
        receivedStream = myHttpWebResponse.GetResponseStream();

        MemoryStream streamReceivedCopy = new MemoryStream();                       
        ImageUtils.CopyStream(receivedStream,streamReceivedCopy);
        var imageType = ImageUtils.GetImageMIMEType(streamReceivedCopy);
        streamReceivedCopy.Position = 0;
        imagelink = new LinkedResource(streamReceivedCopy, imageType);
        imagelink.ContentId = match.Groups[1].Value;
        imagelink.TransferEncoding = System.Net.Mime.TransferEncoding.Base64;
        htmlView.LinkedResources.Add(imagelink);
    }
}
mail.AlternateViews.Add(htmlView);

然后我们使用.net SmtpClient发送电子邮件

Answer 1

我们设法追踪错误：它只是一个部署的旧库导致错误。旧库缺少这些代码行

myHttpWebRequest.UseDefaultCredentials = true;
myHttpWebRequest.PreAuthenticate = true;
myHttpWebRequest.Credentials = CredentialCache.DefaultCredentials;

抱歉！ :(