Best cron job method for email notifications?

There are so many ways to do cron jobs in Rails (Backgroundrb, script/
runner, etc.) but I am wondering what would be the best to use in
production, just for sending out email/SMS notifications? For example,
an email automatically gets sent a day before the due date of a
project milestone.

Thanks for the help!

I've tried BackgroundDRB but wasn't too pleased with it on large-scale
application, it runs slowly, but on small-sized it works just fine.

The solution that works best for me is having rake tasks called from
cron jobs.