Delaying emails in PHP to avoid exceeding server limit

Question

Okay, so here's my problem:

I have a list of members on a website, and periodically one of the admins my site (who are not very web or tech savvy) will send a newsletter to the memberlist. My current memberlist is well over 800 individuals long.

So, I wrote an email script that sends the email to the full memberlist, with the members listed in the Bcc header.

However, I've discovered that my host server has a limit of 300 emails per hour, which I apparently exceed even though the members are listed in the Bcc field. (I wasn't previously aware that the behaviour of Bcc was to send separate emails for each name on the list...)

After some thought, I've come to the conclusion that my only solution is to have my script send only the email to only the first 300 emails, wait an hour, and send a second email to the next three hundred, wait another hour, and so on until I've sent the email to the whole member list.

Looking around on the internet, I've seen some other solutions people have come up with for delaying emails in PHP. Sleep() is obviously not an option, because I can't just leave the script open and running for 3 or four hours. I've seen some people suggest cron jobs, but I'm not sure how feasible it would be to create three new cron jobs every time I send an email, use them once, and then delete them afterward. The final (and what I think is the smartest) solution I've seen, is to have a table in my database to temporarily store the emails to be delayed and sent later, and then create a cron job that checks this sql table every hour or so, compares the timestamp of the row to the current timestamp, and then sends the email if an hour has passed.

So I'm asking you all which method you would recommend. Is there an easier solution that I've completely looked over (aside from getting a different hosting plan. ha!), or is there a cleaner way to do it than the database / cron job approach?

tl;dr: I have >800 emails to send in an hour on a server that limits me to 300/hr. Using PHP, find a way to get around this problem in a way that the person sending the email needs only to click "send."

Answer 1

Sounds like you need to setup a batching function that pulls from a pool of messages to be sent and processes X everytime its run during cron. Then you would have a table that tracks messages that were sent and to who, so you can keep track of who has received emails.

Answer 2

You could send this into a gearman queue and then have a gearman worker with the appropriate sleep calls. See http://gearman.org/ and http://php.net/gearman

Answer 3

I would recommend that you create a queue, and process X number of items from the queue each time you need to send email. The sender of the messages just places the email in the queue and your processing code picks up the item sending the maximum number of items in that period. Occasionally you will have failures and use of the queue will allow simple recovery. You only remove items from the queue when they are processed.

You can use a simple database table to act as the queue but you may prefer to use a specialist queuing solution.

Another recommendation would be to look into external email services like Strongmail. These will help you send more email per hour.