- $headers['Cc'] = CRM_Utils_Array::value('cc', $params);
- $headers['Bcc'] = CRM_Utils_Array::value('bcc', $params);
+
+ // On some servers mail() fails when 'Cc' or 'Bcc' headers are defined but empty.
+ foreach (['Cc', 'Bcc'] as $optionalHeader) {
+ $headers[$optionalHeader] = CRM_Utils_Array::value(strtolower($optionalHeader), $params);
+ if (empty($headers[$optionalHeader])) {
+ unset($headers[$optionalHeader]);
+ }
+ }
+