+function sanitize_email( $email ) {
+ // Test for the minimum length the email can be
+ if ( strlen( $email ) < 3 ) {
+ return apply_filters( 'sanitize_email', '', $email, 'email_too_short' );
+ }
+
+ // Test for an @ character after the first position
+ if ( strpos( $email, '@', 1 ) === false ) {
+ return apply_filters( 'sanitize_email', '', $email, 'email_no_at' );
+ }
+
+ // Split out the local and domain parts
+ list( $local, $domain ) = explode( '@', $email, 2 );
+
+ // LOCAL PART
+ // Test for invalid characters
+ $local = preg_replace( '/[^a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]/', '', $local );
+ if ( '' === $local ) {
+ return apply_filters( 'sanitize_email', '', $email, 'local_invalid_chars' );
+ }
+
+ // DOMAIN PART
+ // Test for sequences of periods
+ $domain = preg_replace( '/\.{2,}/', '', $domain );
+ if ( '' === $domain ) {
+ return apply_filters( 'sanitize_email', '', $email, 'domain_period_sequence' );
+ }
+
+ // Test for leading and trailing periods and whitespace
+ $domain = trim( $domain, " \t\n\r\0\x0B." );
+ if ( '' === $domain ) {
+ return apply_filters( 'sanitize_email', '', $email, 'domain_period_limits' );
+ }
+
+ // Split the domain into subs
+ $subs = explode( '.', $domain );
+
+ // Assume the domain will have at least two subs
+ if ( 2 > count( $subs ) ) {
+ return apply_filters( 'sanitize_email', '', $email, 'domain_no_periods' );
+ }
+
+ // Create an array that will contain valid subs
+ $new_subs = array();
+
+ // Loop through each sub
+ foreach ( $subs as $sub ) {
+ // Test for leading and trailing hyphens
+ $sub = trim( $sub, " \t\n\r\0\x0B-" );
+
+ // Test for invalid characters
+ $sub = preg_replace( '/^[^a-z0-9-]+$/i', '', $sub );
+
+ // If there's anything left, add it to the valid subs
+ if ( '' !== $sub ) {
+ $new_subs[] = $sub;
+ }
+ }
+
+ // If there aren't 2 or more valid subs
+ if ( 2 > count( $new_subs ) ) {
+ return apply_filters( 'sanitize_email', '', $email, 'domain_no_valid_subs' );
+ }
+
+ // Join valid subs into the new domain
+ $domain = join( '.', $new_subs );
+
+ // Put the email back together
+ $email = $local . '@' . $domain;
+
+ // Congratulations your email made it!
+ return apply_filters( 'sanitize_email', $email, $email, null );