I agree, there are two feature requests here. One relates to user deletion/clean up, the other relates to user engagement. I agree that both probably would be doable with auto moderator, but it needs some work to get that functional.
user engagement
Offer functionality in the form of an open source extension, where:
- an extension admin setting is introduced to allow the admin to configure the period after the last log in of a member, upon which an email has to be sent
- allow customizing email template, preferably using fof/pretty-mail
- introduce the console command that is added to the scheduled tasks to process these emails based on setting and template
stale account deletion
Offer functionality in the form of an open source extension, where:
- an extension admin setting is introduced to allow the admin to configure the period after the last log in of a member, upon which a member is supposed to be deleted
- introduce a permission group so that the admin can choose which permission groups should be valid for deletion
- introduce the console command that is added to the scheduled tasks to process these account deletions
In case you want these two to be made into crowdfunded tasks, it would probably be best to split them both out into new topics, with their requirements added as well.