CODEWITHSUNDEEP
c#asp.netemail
Antoine Pelletier
Antoine Pelletier

Reputation: 3326

yahoo and hotmail being capricious with mail sending

We're quite aware of "spam bocking" and "blacklists". And i made all my code according to the "dodge the spam blockers plan" we had. (for good purpose)

Here's the PLAN :

Considering a list of 1500 persons, i'm going to send these emails ONE BY ONE, even doing a pause of 20 secondes every 100 mails, and after like 15 minutes, it will be all good. using this c# code in a validation loop :

    private static bool EnvoieCourriel( string dest, string messsage, string title, string sender)
    {
        SmtpClient smtp = new SmtpClient();
        MailMessage msg = new MailMessage();
        msg.From = new MailAddress(sender);
        msg.Subject = title;
        msg.Body = message;
        msg.IsBodyHtml = true;

        try
        {
            msg.To.Add(dest);
            smtp.Send(msg);
        }
        catch
        {
            return false;
        }

        return true;
    }

Taking logs of this, we went through 10,000 emails sent without any problem, having the confirmation that all the mails as been received correctly.

Then we began to have problems.

With the next 2,000 mails, sometimes, for an ambiguous reason, Yahoo and Hotmail users did not receive their mails.

When i test it on my own Hotmail or yahoo... everything seems to pass through, so what is causing these mails to bounce back cannot really be verified as i don't really intend to send 1500 mails for the sake of debugging (plus i think it wont help) but i suppose it's because too much emails as been sent from the same sender.

Searching :

Sending email to yahoo and hotmail users?

So i'm not the only one that noticed these 2 aren't helping much.

I'm even considering this :

Register my custom domain to google apps, and will open an gmail account with own domain. Then I will send email through google mail server. YOU, nov - 2009

As my potential solution, even though i don't really know how to do that in my context.

So my question is... kind of long...

What's with them ? Hotmail and Yahoo ? How did i manage to dodge the spam block for 10,000 emails and not for the next 10,000 ? Why is it not ALWAYS blocking me then ? (quantity of emails ?) How can i acomplish such task without having to ask for another "emails expert" compagny to send them for me ?

Upvotes: 0

Views: 155

Answers (1)

PhillipH
PhillipH

Reputation: 6222

All large scale mail endpoints maintain dynamic blacklists of senders who generate too many emails. Some do it using "mails per minute", some do it "total mails in 24 hours". I've had the same experience as you with some UK mail endpoints (you will find BT and PlusNet - both UK ISPs - will give you similar 'problems')

The ONLY way to make sure you are not treated as a spam generator (which, in effect, you are) is to open a dialog with the specific company running the endpoint and convince them that you are not generating commercial spam. This isn't something you are going to be able to do unless you are a large company, and have a reasonable market reputation.

Given that these email providers undertake to prevent their customers receiving unsolicited emails (spam) even if your intentions were not to send commercial spam, you might find they are simply not willing to let your mail through.

Tough world.

In some cases you will get an "undeliverable" reply with an SMTP code indicating what the problem was, and on other occasions you will just get nothing at all, and neither will your recipient.

Upvotes: 1

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