diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index 65c017e3dad..e500a5eaba7 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -171,7 +171,7 @@ class CMailFile
 		if (!empty($this->sendcontext)) {
 			$smtpContextKey = strtoupper($this->sendcontext);
 			$keyForSMTPSendMode = 'MAIN_MAIL_SENDMODE_'.$smtpContextKey;
-			$smtpContextSendMode = $conf->global->{$keyForSMTPSendMode};
+			$smtpContextSendMode = empty($conf->global->{$keyForSMTPSendMode}) ? '' : $conf->global->{$keyForSMTPSendMode};
 			if (!empty($smtpContextSendMode) && $smtpContextSendMode != 'default') {
 				$this->sendmode = $smtpContextSendMode;
 			}