Add specific exception in case of GPG encryption failing

exceptions/MDMailerEncryptionFailedException.php

@@ -0,0 +1,18 @@
+<?PHP
+declare(strict_types = 1);
+
+/**
+ * Exception to be thrown
+ */
+final class MDMailerEncryptionFailedException {
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        return 'GPG encryption failed';
+
+    }
+}

src/MDMailerHelper.php

@@ -43,11 +43,16 @@ final class MDMailerHelper {
         }
 
         if ($gpg->addsignkey(MD_CONF_EMAIL::PGP_ENC_KEY) === false) {
-            throw new \Exception("Cannot set private key for GPG encryption");
+            throw new \MDMailerEncryptionFailedException("Cannot set private key for GPG encryption");
         }
 
+        try {
             if (empty($msg = $gpg->encrypt($msg))) {
-            throw new \Exception("Failed to sign and encrypt the message");
+                throw new \MDMailerEncryptionFailedException("Failed to sign and encrypt the message");
+            }
+        }
+        catch (Exception $e) {
+            throw new MDMailerEncryptionFailedException("Failed to sign and encrypt the message to " . $to);
         }
 
         return $msg;