diff --git a/src/MDMailerHelper.php b/src/MDMailerHelper.php
index 612b0d8..213e2ae 100644
--- a/src/MDMailerHelper.php
+++ b/src/MDMailerHelper.php
@@ -26,14 +26,14 @@ final class MDMailerHelper {
         $gpg->seterrormode(GNUPG_ERROR_EXCEPTION);
 
         if (empty($recipients = $gpg->keyinfo($to))) {
-            throw new \Exception("Cannot retrieve public key of recipient for GPG encryption");
+            throw new \Exception("Cannot retrieve public key of recipient for GPG encryption for mail address: " . $to);
         }
 
         foreach ($recipients as $recipient) {
             $recipient_fingerprint = $recipient["subkeys"][0]["fingerprint"];
 
             if (empty($recipient = $gpg->addencryptkey($recipient_fingerprint))) {
-                throw new \Exception("Cannot set public key of recipient for GPG encryption");
+                throw new \Exception("Cannot set public key of recipient for GPG encryption for user: " . $to);
             }
 
         }