It's easy enough for someone to comment why they flagged a post, but maybe just for the case that the flagger wants it to be anonymous and still let the person know why they were flagged there should be an option that allows users to let people know why they got flagged. I think it would help people to better learn from their mistakes and maybe also prevent some unnecessary flagging.
I think the better of my ideas would be for mods to be able to somehow automatically notify somebody of a question being deleted. I think that when questions are deleted or if a mod doesn't let a question pass through the site they should be able to click a reason as to why so that the person asking/who asked the question understands what they did wrong.
Since nobody's perfect I'll admit that I've submitted about two questions earlier on when I wasn't as familiar with the rules as I am now, and as soon as I did realized it was against a certain rule, then thought "well, thankfully we have those moderators to check them over." Then I also had to think to myself that what if I was somebody who wasn't aware of my mistake, and would never know why my question didn't go through, or maybe got deleted?
Yes, obviously people should read the rules when they sign up, but in the case that somebody didn't or forgot a few, then I think it would do good for them to know why their post isn't allowed. It doesn't have to be too much work either, just a quick optional click from a series of reasons that will be submitted and sent to the person in their updates.
Sorry for making this long.