Queue messages and send them out in small batches

[Kristina Hoeppner]

When a Mahara training is taking place on a site and pages / collections are created in / shared with a group and "Shared page notifications" are turned on, a lot of emails can be generated. When they are sent out they can result in a mail server to reject them esp. if all users have the same email domain.

It would be better if a queue was established and sent out in smaller batches so that mail servers don't blackmail the sender.

[Aaron Wells (u-aaronw)]

I did some initial work towards this under Bug 1284887.

Honestly, I feel like in a perfect world this would be something that your friendly sysadmin could configure your mail server to deal with. Kind of like how denial-of-service stuff is also better handled at the server level.

But this is a less-than-perfect world, so we may as well tackle it in Mahara.

The implementation route I took, was to create a mail_queue table in the Mahara database. All emails sent to users in Mahara go through the function "email_user()", so instead of making this function actually send the email, we would make it insert into the mail_queue table.

A later cron task would then take the most recent X emails from mail_queue and actually send them out. The number of messages to send out on each cron task, would be configurable.

[Kristina Hoeppner (kris-hoeppner)]

Aaron's solution is sufficient right now until we need to make more changes.