I am looking for the ability to automatically delete users who remain in the 'email_confirm' state for too long. For instance, if a user registers, and doesn't confirm their email for 2 weeks, I would like to get their account purged. The reason for this is to clean up spam. Often a spam bot will register 500+ accounts over the course of a month, that will just lie in wait on the forum. Then randomly several months later they will all verify their emails and start spamming.
There is a mod for this in vBulletin, but it was problematic because if someone changed their email address, they were put in risk of getting their account deleted; even though they were previously verified users. Because of XenForo's 'email_confirm_edit' feature, this issue has already been resolved! You should also be able to set a maximum post requirement.