diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index bd24760030a..f43912237cc 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -686,6 +686,8 @@ class CMailFile
 					$this->error .= '<br>'.$langs->trans("MailSendSetupIs3", $conf->global->MAILING_SMTP_SETUP_EMAILS_FOR_QUESTIONS);
 					$this->errors[] = $langs->trans("MailSendSetupIs3", $conf->global->MAILING_SMTP_SETUP_EMAILS_FOR_QUESTIONS);
 				}
+
+				dol_syslog("CMailFile::sendfile: mail end error=".$this->error, LOG_WARNING);
 				return false;
 			}