Emailing subscribers is somewhat of a complicated problem. On the one hand, I want subscribers to find out about all the latest free food events. On the other hand, I don't people to get spammed by too many emails. I revamped the entire mailing system keeping these two goals in mind, and I think the new system does a good job of accomplishing both.
Here's how it works:
Every week a mailing daemon runs and notifies subscribers of any events coming up this week that have never been announced before. This keeps down the amount of emails, but still notifies users in a timely manner of newly added free food events.
If a new free food event is discovered that will occur within the week (before the next time the daemon will run), users will be notified immediately of the event so that they have a chance to find out about it in time.
And just as a fail-safe, I implemented a small upper-bound on the number of times subscribers can be emailed within 24 hours.
This new system basically notifies subscribers in a timely way. If an event is found that is happening soon, the subscribers are notified. If an event is found that is happening later, the notification is deferred.
I think the new mailing system will help inform subscribers in a way that is both useful and not annoying.