General Setting Allow Multiple Email Notification

It’s not really a WP-specific solution, but if you set up a Gmail address (and likely others), you could create a filter to automatically forward notifications generated by WordPress to other admins. Short of WordPress adding multi-email notifications, that might be a workaround to temporarily solve the problem.

Disable WP notifications for commenting on own posts

The function that sends emails to the post author is called wp_notify_postauthor() and is located in /wp-includes/pluggable.php. This means that the function is “pluggable” and can be overridden by another function with the same name. We can make a simple plugin to do this. This is the code we’ll be adding to the function to … Read more

Sanitizing and validating email field

According to the documentation, is_email() is used to validate an email and either returns the email if it is valid or false if it isn’t. So are using it correctly. The only thing I can see in your code is that if the email is not valid, you are settings the data to a boolean … Read more

apostrophe in email name

Filter is_email and sanitize_email, then apply a better check: namespace Wpse\Email; add_filter( ‘is_email’, __NAMESPACE__ . ‘\check_mail_address’, 10, 2 ); add_filter( ‘sanitize_email’, __NAMESPACE__ . ‘\check_mail_address’, 10, 2 ); function check_mail_address( $result, $email ) { return filter_var( $email, FILTER_VALIDATE_EMAIL ); } The PHP function is still not RFC 5321 compliant, but better than the WordPress check.

Joining confirmation email

Not sure how to close this post. I used WP better emails plugin http://wordpress.org/extend/plugins/wp-better-emails/ on the subsites and it removed the wordpress email address. (I was only using it on the main site before so it didn’t work.) Thanks.