Preventing users with low karma and account age from STARTING to post or reply

We have account age and karma limits set up in our automod, and we get lots of angry modmail about it. One user asked why we couldn't let him know that he didn't meet our limit BEFORE he spent 15 minutes composing the perfect response, only to discover that his excellent reply was not permitted. I had to agree with him. Would there be a way for the automoderator to add text somewhere saying something like 'You cannot post here yet due to low karma. See Rule 8."