diff --git a/src/Common/FormData.php b/src/Common/FormData.php
index 8041257..3796e18 100644
--- a/src/Common/FormData.php
+++ b/src/Common/FormData.php
@@ -46,7 +46,7 @@ abstract class FormData
 
     private static function validateMailAddress(string $address, bool $required = true, string $fieldName = 'Mail address'): ?string
     {
-        // Note: This validator allows '%' as wildcard character inside mail addresses.
+        // Note: This validator allows '%' as wildcard character inside the username of mail addresses.
         if (!$required && $address === '') {
             return null;
         }
@@ -55,7 +55,7 @@ abstract class FormData
             self::validateString($address, 3, 100, $fieldName)
         );
 
-        if (!preg_match('/^[a-z0-9%._+-]+@[a-z0-9%.-]+$/', $address) || preg_match('/^\\.|\\.\\.|\\.@|@\\.|\\.$/', $address)) {
+        if (!preg_match('/^[a-z0-9%._+-]+@[a-z0-9.-]+$/', $address) || preg_match('/^\\.|\\.\\.|\\.@|@\\.|\\.$/', $address)) {
             throw new InputValidationError("$fieldName is not valid (must be a valid mail address).");
         }
         return $address;