In a recent note to developers, Facebook announced that because app emails have been so spammy, user emails will be turned off by default when users add apps. Previously, this option was presented to users on the app installation page, checked on by default. Facebook writes,
We know that email is an important communication channel for many of you to reach users. However, we’ve also seen a surprisingly high number of users mark application email as spam instead of simply unsubscribing from it. In order to preserve email as a channel for high quality communications, email to users is disabled by default. Instead, you can offer users a way (such as an FBML button or an FBML attribute you can append to your own link or button) to opt-in to receiving email from your application on your canvas page.
While many Facebook app developers have been sending spammy emails, turning email off by default for all app developers seems an overly severe policy change. Facebook should just tweak the email allocation limits based on user feedback as they have been doing at a more granular level.