PHP Mass Email Best Practices? (PHPMailer + Gmail)

Question

Hey everyone,

I'm thinking about how to handle sending large amounts of email from my web applications, and whether there are any best practices for doing so. StackOverflow is already labeling this as 'subjective', which it may be to an extent, but I need to know the most successful way to implement this system, or whether any standardized approach exists.

In my webapp, there are users who are heads of groups of 1 to 10,000 users. This user must be able to email send a message to all of these users through my system. Therefore, my system is responsible for sending up to 10,000 emails to individual users for each group head.

As far as I can tell, there is no rate limit in GMail for sending messages to individuals (although there is a 500 recipient max).

Right now, my current setup is:

• When a message is sent through the system, it enters an email queue.
• A cron script grabs messages from the queue every few minutes, and sends out those emails.
• All email is taking place through GMail's SMTP server.
• The actual application doing the mailing is PHPMailer.

This setup, as the user base grows, will probably not suffice. The questions I have are:

1. Should I be using a local SMTP server instead?
2. Should I use a mail binary on the local machine instead? I this case, I could probably skip the queue altogether?
3. Is there an accepted way to do this?

Thanks!

Answer 1

Gmail and Google Apps limits you to around 500 emails a day. I'm not sure how that combines with the 500 recipient max, but if you want to send 10 000 emails you'll probably want to find another mail server. I personally use a local server or the ISP or datacenter's SMTP.

If you are sending that many emails, I would recommend using the queue so the user's isn't sitting there waiting for the email to be sent.

Answer 2

With an email count as "high" as 10.000 a day, I wouldn't rely on GMail (or any other) SMTP. Not that they can't handle it, obviously they can handle A LOT more. But they possibly don't want to.

Having a local SMTP server is IMO the way to go :

• It's pretty easy to set up (just DON'T let people use it without a strong authent scheme)
• Most modern MTA handle sending queues very well
• You won't have to deal with GMail (or others) deciding to block your account someday for quota reasons

Answer 3

Google App Engine

I would write this in Google app engine (python) because:

• It scales well.
• It has a good email api.
• It has a taskqueue with a good api to access it.
• Because python is a real nice language.
• It is (relatively) cheap.

PHP

If I would implement it in PHP I would

• Find yourself a good SMTP server which allows you to sent this volume of mails because Gmail will not allow you to sent this kind of volume. I am for sure that this will cost you some money.
• Find yourself a decent PHP email library to sent messages with like for example PHPMailer like you said.
• Use a message queue like for example beanstalkd to put email messages in queue and sent email asynchronously. First because with this the user will have snappier page load. Second with a message queue like beanstalkd you can regulate speed of sending better which will prevent from overloading your pc with work. You will need to have ssh access to the server to compile(install) beanstalkd. You can find beanstalkd at beanstalkd
• You would also need ssh access to run a PHP script in the background which will process the message queue. You can find a beanstalkd-client at php beanstalkd-client

from php/apache/webpage

This is the page from which you will sent messages out to user. From this page you will sent message to beanstalkd by coding something in the lines of this:

// register Pheanstalk class loader
require_once('pheanstalk_init.php');
$pheanstalk = new Pheanstalk('127.0.0.1');
$message = ""; // This would contain your message
$pheanstalk->put(json_encode($message);

You have to put messages in message queue using put command

From long running PHP script in background:

The code would look something like this:

// register Pheanstalk class loader
require_once('pheanstalk_init.php');
$pheanstalk = new Pheanstalk('127.0.0.1');

while(true) {
  $job =  $pheanstalk->reserve();
  $email = json_decode($job->getData());
  // Sent email using PHP mailer.
  $pheanstalk->delete($job);
}

Like I am saying it is possible with both PHP and Google app engine but I would go for app engine because it is easier to implement.

Answer 4

Be very careful that your domain doesn't get blacklisted as a spam domain. If it does, you can expect most of your emails to be blocked, support, sales, etc. Which could in turn be very expensive.

You may instead want to use a service like AWeber. Not only are they setup to handle these amounts of emails, but they can probably give you more metrics than you can implement on your own.

Answer 5

I'm not sure if it's publishe anywhere, but from experience I can tell you that Gmail will put a fifteen minute or so freeze on your account if you start sending hundreds of messages at a time. This happened to me last week. I think you should host your own SMTP server. Using the mail() function often will put your mail in someone's spam folder.