As you have said that you have already tried disabling plugins and consulted hosting provider, there must be an issue with the WordPress version. Would you please tell me the version number? Today, v5.0.1 has been released. You should try installing it.
You can try using Greg’s Comment Length Limiter. It provides you with a configurable limit on the length of comments.
Unable to view comments on my website
No comments allowed
I have fixed this, though I must “style” things better with CSS. In short my theme was not completely updated to WordPress 2.7. I needed one line of code in header.php and a few changes to comments.php it is all detailed on Ottodestruct.
I would probably approach this with a wp_mail filter to catch these messages before they are sent. That would be the simplest approach in my opinion. You could create a filter function to screen email content and use key elements unique to these emails. My example will just target “New comment on your post” contained … Read more
Please make sure that you have turned on the comments and discussion from the screen options of the posts => http://prntscr.com/m8qac1 And also mark the check mark on the allow comments checkbox showing on the middle/end of the post pages => http://prntscr.com/m8qapd
Although it would be useful to determine why the extra notifications are sent (forwarding settings?), there is a way to adjust who gets notification emails when a comment is posted (which is what you asked, not how to fix the problem): // adds emails to the ‘notify admins on comment submit’ // from http://www.sourcexpress.com/customize-wordpress-comment-notification-emails/ // … Read more
How to get_comments() ordered by date and parent?
WordPress weird behaviour on comments