wp-includes/ms-functions.php:399Checks an email address against a list of banned domains.
$user_emailstringboolOne hook fires while is_email_address_unsafe() runs, in this order:
Filters whether an email address is unsafe.
function is_email_address_unsafe( $user_email ) { $banned_names = get_site_option( 'banned_email_domains' ); if ( $banned_names && ! is_array( $banned_names ) ) { $banned_names = explode( "\n", $banned_names ); } $is_email_address_unsafe = false; if ( $banned_names && is_array( $banned_names ) && false !== strpos( $user_email, '@', 1 ) ) { $banned_names = array_map( 'strtolower', $banned_names ); $normalized_email = strtolower( $user_email ); list( $email_local_part, $email_domain ) = explode( '@', $normalized_email ); foreach ( $banned_names as $banned_domain ) { if ( ! $banned_domain ) { continue; } if ( $email_domain === $banned_domain ) { $is_email_address_unsafe = true; break; } if ( str_ends_with( $normalized_email, ".$banned_domain" ) ) { $is_email_address_unsafe = true; break; } } } /** * Filters whether an email address is unsafe. * * @since 3.5.0 * * @param bool $is_email_address_unsafe Whether the email address is "unsafe". Default false. * @param string $user_email User email address. */ return apply_filters( 'is_email_address_unsafe', $is_email_address_unsafe, $user_email );}Introduced in MU (3.0.0). Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/ms-functions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.