Issue with Gmail - Embedded images using MailKit

Question

I'm trying to send emails with embedded images using MailKit. It works well on MS Outlook. However, images do not display as embedded images in Gmail. I tried to attach with "data:image/png;base64," format to it also worked on Outlook but not Gmail.

Any help would be much appreciated!

public string SendEmail (MyModel myModel)
{
    var message = new MimeMessage();
    var bodyBuilder = new BodyBuilder
    {
        HtmlBody = myModel.Body
    };
    GetAllImgTags(bodyBuilder);
    message.Body = bodyBuilder.ToMessageBody();
    // Send Email Here...
    return "OK"
}

    public string GetAllImgTags(BodyBuilder bodyBuilder)
    {
        HtmlDocument document = new HtmlDocument();

        document.LoadHtml(bodyBuilder.HtmlBody);

        var imgList = document.DocumentNode.Descendants("img").Where(x =>
        {
            string src = x.GetAttributeValue("src", null) ?? "";
            return !string.IsNullOrEmpty(src);
        }).ToList();

        foreach(var item in imgList)
        {
            string currentSrcValue = item.GetAttributeValue("src", null);
            var file = Path.Combine(_env.WebRootPath,"images", currentSrcValue);
            if (File.Exists(file))
            {                    
                byte[] imageData = System.IO.File.ReadAllBytes(file);
                string contentId = string.Format("{0}@{1}", Path.GetFileName(file), Guid.NewGuid().ToString());
                LinkedResource inline = new LinkedResource(new MemoryStream(imageData), Image.Jpeg)
                {
                    ContentId = contentId,
                    TransferEncoding = TransferEncoding.Base64,
                    ContentLink = new Uri("cid:" + contentId),

                };
                inline.ContentType.Name = contentId;
                inline.ContentType.MediaType = Image.Jpeg;
                bodyBuilder.LinkedResources.Add(contentId, new MemoryStream(imageData));

                item.SetAttributeValue("src", "cid:" + contentId);
                inline.Dispose();
            }
        }

        bodyBuilder.HtmlBody = document.DocumentNode.OuterHtml;
        string result = document.DocumentNode.OuterHtml;
        return result;
    }

Answer 1

Well, first of all, why are you creating System.Net.Mail objects and then simply disposing them without using them in any way?

See this code for what I mean:

LinkedResource inline = new LinkedResource(new MemoryStream(imageData), Image.Jpeg)
{
    ContentId = contentId,
    TransferEncoding = TransferEncoding.Base64,
    ContentLink = new Uri("cid:" + contentId),
};
inline.ContentType.Name = contentId;
inline.ContentType.MediaType = Image.Jpeg;

Let's try this instead:

var contentType = new ContentType ("image", "jpeg");
var contentId = MimeKit.Utils.MimeUtils.GenerateMessageId ();
var image = (MimePart) bodyBuilder.LinkedResources.Add (file, contentType);
image.ContentTransferEncoding = ContentEncoding.Base64;
image.ContentId = contentId;

item.SetAttributeValue ("src", "cid:" + contentId);