Can please teach me which function reference should I use to modify new user email notification in network admin screen -> add user.
I want to use custom email template for notify user?
it will be very helpful if you can give example because documentation is still not complete for wordpress multisite.
Muhammad,
Multisite uses the same code in most cases. If you look at the function https://developer.wordpress.org/reference/functions/wp_new_user_notification/, you'll see that there are filters to change the 'message', such as 'wp_new_user_notification_email_admin' and 'wp_new_user_notification_email'.
You'll see the code includes link to "network_site_url" allowing for a new ms user.
A good way to teach oneself these things is to have multisite on a localhost, then you can tracks, search, explore the code and verify what functions are executing and see what filters are being applied and actions being 'done'.
