Attaching Image in the body of mail in C#

Solution 1:

    string attachmentPath = Environment.CurrentDirectory + @"\test.png";
    Attachment inline = new Attachment(attachmentPath);
    inline.ContentDisposition.Inline = true;
    inline.ContentDisposition.DispositionType = DispositionTypeNames.Inline;
    inline.ContentId = contentID;
    inline.ContentType.MediaType = "image/png";
    inline.ContentType.Name = Path.GetFileName(attachmentPath);

    message.Attachments.Add(inline);

reference: Send an Email in C# with Inline attachments

Solution 2:

Use so called LinkedResource. Here you can find how-to. Have done that successfully.

If tutorial does not help, don't be shy and ask for clarification. :)