I’m sure due to not properly posting the ads, like irrelevant content and categories you people might block such user from posting the ads.

Existing system: when anyone gets blocked from posting the ads there’s no option of updating user about it, thus the reason users still unaware of it that their email id has blocked from posting the ads and they keep on try to post new ads which is indeed comes under very bad user experience.

My suggestion : when any user gets blocked from posting ads just send him the notification about it so that he will send any requesting mails or make any standard policies on it so that users will not have to waste time on something which is not possible without approaching to one of your admins.

I hope it will definitely helps you to make your platform more user friendly.
Thanks