Hi there,

Kindly find my response to your inquiries below:
In my website I am unable to get ES notifications when I comment on a blog that I created in EB.
-> You will not get notify to own comment in your blog post (where this is default behavior) You will only get notify if someone else commented in your blog post
*Seems like you did not discover the alert for blog integration yet, I've helped you to discover it and it should notify EasySocial system and email notification now.
If you want to reconfigure it back, go to (Backend>Components>EasySocial>Alerts)

At the same time, when I reply to the blog stream, I dont see that reply under the blog in EB.
-> This is default behavior where as you reply the blog stream generated in EasySocial, it will not saved in the blog post in EasyBlog.

When I login as registered user, I also find a header saying "Notice: Could not instantiate mail function."
-> This issue is more related to Joomla instead of our component to be honest.
Perhaps, can you refer this article: https://www.templatemonster.com/help/joomla-3-x-how-to-fix-could-not-instantiate-mail-function-error-in-contact-form.html#gref