diff --git a/src/Symfony/Component/Mime/Part/DataPart.php b/src/Symfony/Component/Mime/Part/DataPart.php
index b1c581e6f64ed..5320df45163f5 100644
--- a/src/Symfony/Component/Mime/Part/DataPart.php
+++ b/src/Symfony/Component/Mime/Part/DataPart.php
@@ -66,7 +66,7 @@ public function asInline(): static
     public function setContentId(string $cid): static
     {
         if (!str_contains($cid, '@')) {
-            throw new InvalidArgumentException(sprintf('Invalid cid "%s".', $cid));
+            throw new InvalidArgumentException(sprintf('The "%s" CID is invalid as it doesn\'t contain an "@".', $cid));
         }
 
         $this->cid = $cid;