Why Does My Embedded Email Image Show as a Red X Instead of Rendering?

Troubleshooting Embedded Email Images: A Content ID Approach

Embedding images directly within email bodies improves readability and user engagement. This is achieved by linking the image to a unique Content ID. However, problems can arise, resulting in the image displaying as a broken red 'X' instead of rendering correctly.

Solution: Correctly Embedding Images with Content IDs

The following code provides a robust solution for embedding images using Content IDs:

<code class="language-csharp">MailMessage mailWithImg = GetMailWithImg();
MySMTPClient.Send(mailWithImg); // Ensure MySMTPClient is properly configured beforehand

private MailMessage GetMailWithImg()
{
    MailMessage mail = new MailMessage();
    mail.IsBodyHtml = true;
    mail.AlternateViews.Add(GetEmbeddedImage("c:/image.png"));
    mail.From = new MailAddress("yourAddress@yourDomain");
    mail.To.Add("recipient@hisDomain");
    mail.Subject = "yourSubject";
    return mail;
}

private AlternateView GetEmbeddedImage(string filePath)
{
    LinkedResource res = new LinkedResource(filePath);
    res.ContentId = Guid.NewGuid().ToString();
    string htmlBody = $"<img src=\"cid:{res.ContentId}\">"; //Simplified HTML
    AlternateView alternateView = AlternateView.CreateAlternateViewFromString(htmlBody, null, MediaTypeNames.Text.Html);
    alternateView.LinkedResources.Add(res);
    return alternateView;
}</code>

Explanation:

This improved code snippet ensures proper image embedding:

• GetMailWithImg() sets up the email message, enabling HTML formatting and adding the embedded image.
• GetEmbeddedImage() handles image loading, assigning a unique Content ID via Guid.NewGuid(), and correctly formats the HTML <img> tag. Note the simplified and corrected HTML.
• The AlternateView is correctly constructed and added to the MailMessage.

Advantages of this Method:

This approach embeds the image directly into the email, improving visual appeal and avoiding the need for separate attachments. This leads to a cleaner, more professional email presentation.

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