--- a/src/Header/AbstractAddressList.php
+++ b/src/Header/AbstractAddressList.php
@@ -152,7 +152,10 @@
                 }
             }
 
-            if (empty($name)) {
+            if (
+                empty($name)
+                || !HeaderValue::isValid($name)
+            ) {
                 $emails[] = $email;
             } else {
                 $emails[] = sprintf('%s <%s>', $name, $email);