FWIW, I had this happen on my site this week, and for a longtime email-only user (a trusted staff colleague of mine, in fact) who was surprised and a bit annoyed to get the automated message below from me in response to a post. I wrote in another topic about email only users needing an automatic pathway to full citizenship.
In the case of this automated email, it says “multiple community members flagged this post before it was hidden” which in this case I know is not true. She was just still a TL0 new user (because she rarely logs in) and hit a linking threshold that triggered the automatic flagging.
So some more granularity in the reason given for the flagging would be helpful. Both for the user trying to post and for moderators trying to help users caught in this predicament. I am not sure at all how best to do this (maybe templates with a dedicated spot to insert the reason?) and it’s not been a big issue yet on my site - we very rarely get flagged posts.