画像を埋め込みリソースとして使用する例を次に示します。
MailMessage message = new MailMessage();
message.From = new MailAddress(fromEmailAddress);
message.To.Add(toEmailAddress);
message.Subject = "Test Email";
message.Body = "body text\nblah\nblah";
string html = "<body><h1>html email</h1><img src=\"cid:Pic1\" /><hr />" + message.Body.Replace(Environment.NewLine, "<br />") + "</body>";
AlternateView alternate = AlternateView.CreateAlternateViewFromString(html, null, MediaTypeNames.Text.Html);
message.AlternateViews.Add(alternate);
Assembly assembly = Assembly.GetExecutingAssembly();
using (Stream stream = assembly.GetManifestResourceStream("SendEmailWithEmbeddedImage.myimage.gif")) {
LinkedResource picture = new LinkedResource(stream, MediaTypeNames.Image.Gif);
picture.ContentId = "pic1"; // a unique ID
alternate.LinkedResources.Add(picture);
SmtpClient s = new SmtpClient();
s.Host = emailHost;
s.Port = emailPort;
s.Credentials = new NetworkCredential(emailUser, emailPassword);
s.UseDefaultCredentials = false;
s.Send(message);
}
}