RFC 5322 Support for is_email() function. Quick fix.

Today I received a email from my client where he mentioned that he is unable to login to the members area on my website with his email which contains “+” symbol.

I was quite suprised when I tested his email something+something@anything.com and found out that the default WordPress function is_email() returns false for this type of emails. In other words, is_email() function isn’t able to validate email addresses with a “+” in it but those are valid email addresses as well as per RFC standard 5322. By the way, if you look at the official documentation of is_email() function, there also said that it is not RFC compliant.

Within one hour or so I came to this solution, which can be added to your current theme (child theme) functions.php file:

add_filter( 'is_email', 'misha_is_email_rfc5322', 9999, 2 );
 
function misha_is_email_rfc5322( $true_or_false, $email ) {
 
	$regex = '/^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}@)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\]))$/iD';
 
	if ( ! preg_match( $regex, $email )) {
		return false;
	} else {
		return true;
	}
 
}

I found this regular expression on the website emailregex.com, if you think, that it is not fully correct, please let me know in the comments and let’s figure it out together.

Misha Rudrastyh

Misha Rudrastyh

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