Sending mass email using PHP

I am currently writing a music blog. The administrator posts a new article every 2-3 days. Once the administrator posts an article, a mass email will be sent to around 5000 subscribers immediately.

What is the best way to implement the mass mail feature?

Does the following function work?

function massmail() 
{
  $content = '...';
  foreach ($recipients as $r) {
    $_content = $content . '<img src="http://xxx/trackOpenRate.php?id='.$r.'">';
    mail($r, 'subject', $_content);
  }
}

Another question: If all 5000 subscribers are using Yahoo Mail, will Yahoo treat it as a DDOS attack and block the IP address of my SMTP server?

Solution 1:

First off, using the mail() function that comes with PHP is not an optimal solution. It is easily marked as spammed, and you need to set up header to ensure that you are sending HTML emails correctly. As for whether the code snippet will work, it would, but I doubt you will get HTML code inside it correctly without specifying extra headers

I'll suggest you take a look at SwiftMailer, which has HTML support, support for different mime types and SMTP authentication (which is less likely to mark your mail as spam).

Solution 2:

I would insert all the emails into a database (sort of like a queue), then process them one at a time as you have done in your code (if you want to use swiftmailer or phpmailer etc, you can do that too.)

After each mail is sent, update the database to record the date/time it was sent.

By putting them in the database first you have

1. a record of who you sent it to
2. if your script times out or fails and you have to run it again, then you won't end up sending the same email out to people twice
3. you can run the send process from a cron job and do a batch at a time, so that your mail server is not overwhelmed, and keep track of what has been sent

Keep in mind, how to automate bounced emails or invalid emails so they can automatically removed from your list.

If you are sending that many emails you are bound to get a few bounces.

Solution 3:

This is advice, not an answer: You are much, much better off using dedicated mailing list software. mailman is an oft-used example, but something as simple as mlmmj may suffice. Sending mass mails is actually a more difficult task than it actually appears to be. Not only do you have to send the mails, you also have to keep track of "dead" addresses to avoid your mail, or worse, your mailserver, being marked as spam. You have to handle people unsubscribing for much the same reason.

You can implement these things yourself, but particularly bounce handling is difficult and unrewarding work. Using a mailing list manager will make things a lot easier.

As for how to make your mail palatable for yahoo, that is another matter entirely. For all its faults, they seem to put great stock in SPF and DomainKey. You probably will have to implement them, which will require co-operation from your mail server administrator.

Solution 4:

You may consider using CRON for that kind of operation. Sending mass mail at once is certainly not good, it may be detected as spam, ddos, crash your server etc.

So CRON could be a great solution, send 100 mails at once, then wait a few minutes, next 100, etc.