c# SmtpClient with AlternateView receive blank content on Hotmail Live MSN OUTLOOK.com service

Question

I recently face a new problem. I send email with the SmtpClient Class everything work fine except for one point. When I want to check the render on Microsoft mail service like hotmail the email is blank but when I check the source the content is there. If I check the mail with other service like GMAIL, Exchange or hotmail email on phone I can see the body part of the message.

Here is my smtp class:

public class SmtpEmail {
    private List<string> _to = new List<string>();
    private List<string> _cc = new List<string>();
    private List<string> _cci = new List<string>();
    private List<string> _replyTo = new List<string>();
    private List<Attachment> _attachments = new List<Attachment>();
    private List<AlternateView> _alternateViews = new List<AlternateView>();

    public string Host { get; set; }
    public string User { get; set; }
    public string Password { get; set; }
    public int Port { get; set; }
    public string From { get; set; }
    public string FromName { get; set; }
    public bool IsHTMLBody { get; set; }
    public string Titre { get; set; }
    public string Body { get; set; }

    public List<string> To {
        get { return _to; }
    }

    public List<string> CC {
        get { return _cc; }
    }

    public List<string> CCi {
        get { return _cci; }
    }

    public List<string> ReplyTo {
        get { return _replyTo; }
    }

    public List<Attachment> Attachments {
        get { return _attachments; }
    }

    /// <summary>
    /// Pour ajouter un message en mode text et un message en mode html, il faut mettre la propriété IsHtmlBody à false,
    /// mettre le message texte dans le la propriété Body et mettre le message HTML dans un AlternateView comme ceci:
    /// EX: mail.AlternateViews.Add(System.Net.Mail.AlternateView.CreateAlternateViewFromString(html, new System.Net.Mime.ContentType("text/html")));
    /// </summary>
    public List<AlternateView> AlternateViews {
        get { return _alternateViews; }
    }

    public SmtpEmail(string Host, string User, string Password, int Port, string From) {
        this.Host = Host;
        this.User = User;
        this.Password = Password;
        this.Port = Port;
        this.From = From;
        this.FromName = string.Empty;
    }

    /// <summary>
    /// Constructeur pour l'initialisation de l'envoi du courriel
    /// </summary>
    /// <param name="Host">L'adresse du serveur SMPT</param>
    /// <param name="User">Le nom d'utilisateur du serveur SMPT</param>
    /// <param name="Password">Le mot de passe du serveur SMPT</param>
    /// <param name="Port">Le port du serveur SMPT</param>
    /// <param name="From">L'adresse courriel de provenance du courriel</param>
    /// <param name="FromName">Nom de remplacement pour le courriel. EX: "Nom de la compagnie" [email protected] </param>
    public SmtpEmail(string Host, string User, string Password, int Port, string From, string FromName) {
        this.Host = Host;
        this.User = User;
        this.Password = Password;
        this.Port = Port;
        this.From = From;
        this.FromName = FromName;
    }

    public bool SendMessage() {
        MailMessage message = new MailMessage();
        if(string.IsNullOrEmpty(this.FromName.Trim())) {
            message.From = new MailAddress(this.From);
        } else {
            message.From = new MailAddress(this.From, this.FromName);
        }

        foreach(string email in _to)
            message.To.Add(new MailAddress(email));

        foreach(string email in _cc)
            message.CC.Add(new MailAddress(email));

        foreach(string email in _cci)
            message.Bcc.Add(new MailAddress(email));

        foreach(string email in _replyTo)
            message.ReplyToList.Add(new MailAddress(email));

        foreach(Attachment attachment in Attachments)
            message.Attachments.Add(attachment);

        foreach(AlternateView alternateView in AlternateViews)
            message.AlternateViews.Add(alternateView);

        if(AlternateViews.Count > 0) {
            message.Headers.Add("content-type", "multipart/mixed");
        }

        message.IsBodyHtml = this.IsHTMLBody;
        message.Subject = this.Titre;
        message.Body = this.Body;

        SmtpClient client = new SmtpClient(this.Host, this.Port);
        client.Credentials = new NetworkCredential(this.User, this.Password);

        try {
            client.Send(message);
        } catch {
            return false;
        }

        return true;
    }
}

There when I call my class:

SmtpEmail mail = new SmtpEmail(Smtp.Host, Smtp.Username, Smtp.Password, Convert.ToInt32(Smtp.Port), Smtp.From, "exemple.com");

        mail.To.Add("[email protected]");

        mail.Titre = titre;
        mail.Body = plainText;

        mail.IsHTMLBody = false;

        mail.AlternateViews.Add(System.Net.Mail.AlternateView.CreateAlternateViewFromString(HtmlText, Encoding.UTF8, System.Net.Mime.MediaTypeNames.Text.Html));

        mail.SendMessage();

I saw some solution but nothing work for me: https://stackoverflow.com/a/7811002 https://stackoverflow.com/a/10624176

If you need more information you can contact me.

Answer 1

OK I found the problem in my case. In my email HTML part à have comment in the style section (/**/) and I think outlook.com dont like it. When I remove those comment, my email html part was no more blank.

Answer 2

I had the problem that the html email was completely empty in Hotmail aside for a pdf attachment which was sent along. I solved the problem by paste-ing my code into a html validation site:

http://www.freeformatter.com/html-validator.html

It pointed out that I had not closed a couple of html meta tags in the header with a "/". Closing the tags fixed the problem.