Using php mail VS Pear function for many emails (but slow frequency)

Question

I know that for large amount of emails it is recommended to use Pear but I'm wondering if it is worth digging into it in my case (I installed it but I have many errors coming from PEAR)

I need to send emails to my subscribers (around 20K) but my host only allow 200 emails per hour. This is OK because I don't need everyone to get the e-mail at the same time, I can send all these mails within a month, I'm not in the hurry.

In that case, would it be OK to have a really simple loop that send on email with mail() and then sleep for 18 seconds (to be under 200emails/hour) . Basically, what I'm thinking is simply to do something like this

for($i=0;$i<=count($recipient);$i++)
{
   mail($recipient[$i].....);
   sleep(18);
}

Is this OK vs using PEAR (which require many more time) ?

Answer 1

If your server is linux based, you might get away with that (See this question).

Although this doesn't really sound like a great solution, also taking into account that it seems like you are using a for loop with all your recipients (20k).

If you don't want to use PEAR you might want to try setting up a cron job every hour that somehow (using a text file, or a database) remembers the last user it sent an email to, and sends the next batch of 200.

In that case you might want to setup the cronjon every 125 minutes just to be sure you don't reach the limit. Also using sleep(1); after each mail() will spare CPU.

Check out this question for performance considerations.

Answer 2

Have you looked at using PEAR's Mail_Queue package? http://pear.php.net/package/Mail_Queue ? You can set it to send X many emails in one process and then rerun the same script to send the next X many.

I certainly wouldn't use the native mail function for sending anything more than concise emails, perhaps for notifying you of exceptional conditions in an app.

Answer 3

First, I wouldn't say that the limitations of good old mail()...

• Manual encoding of almost everything
• Poor error handling
• No authentication (though not an issue for you)

... are related to volume.

Second, I've never used PEAR Mail so I can't speak about its performance or overhead but your use case comes precisely from a low-capacity e-mail server. You don't need high performance to do things slowly, do you?

So I'd dare say you're using the wrong criteria to evaluate tools.

My advice is that you leave mail() for extremely simple and unimportant tasks (and subscriber communication does not qualify as such) and use a proper third-party mail library, not necessarily PEAR's.

Particularly, Swift Mailer features Throttler Plugin that's designed to do exactly what you ask for:

If your SMTP server has restrictions in place to limit the rate at which you send emails, then your code will need to be aware of this rate-limiting. The Throttler plugin makes Swift Mailer run at a rate-limited speed.

Many shared hosts don't open their SMTP servers as a free-for-all. Usually they have policies in place (probably to discourage spammers) that only allow you to send a fixed number of emails per-hour/day.

The Throttler plugin supports two modes of rate-limiting and with each, you will need to do that math to figure out the values you want. The plugin can limit based on the number of emails per minute, or the number of bytes-transferred per-minute.