The only reasonable way (efficient, scalable, and cpu friendly) is via cron job. It would eat up tons of cpu cycles if the email functions were called with every hit to one's forum.

To do the cron job is relatively easy I think, but one would have to use Perl and query the database, say, once every hour?

Do you know Perl Freddie? I can help out in this area, but would need to know more specific details since I've not yet looked at the hack's database structure much.


I think by default sending emails out regarding public events should be OFF. Why? Because those usually are not important personal events for users, and some might hate it. Besides, imagine if you have 30,000 users. That would be pretty painful for your mail system.

Just have an option where users can choose to "subscribe" to public events. Start with the least and let users "opt in" for more. Same should go with private events. A check mark for "notify via email" should be there for them.