Now you can enable user mention functionality in post comments without using the BuddyPress plugin.
This plugin is useful for those who want to enable mention on their blog site.
What does this plugin do? Just wring username followed by ‘@’ in the comment box. It will send the email to the mentioned user.
Email setting is provided in the backend. You can change the email subject and content on your own.
This plugin is available free at https://wordpress.org/plugins/comment-mention/