diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index ba657f58087..b3ff0aae930 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -878,7 +878,11 @@ class CMailFile
 					$keyforsupportedoauth2array = preg_replace('/-.*$/', '', $keyforsupportedoauth2array);
 					$keyforsupportedoauth2array = 'OAUTH_'.$keyforsupportedoauth2array.'_NAME';
 
-					$OAUTH_SERVICENAME = (empty($supportedoauth2array[$keyforsupportedoauth2array]['name']) ? 'Unknown' : $supportedoauth2array[$keyforsupportedoauth2array]['name'].($keyforprovider ? '-'.$keyforprovider : ''));
+					if (isset($supportedoauth2array)) {
+						$OAUTH_SERVICENAME = (empty($supportedoauth2array[$keyforsupportedoauth2array]['name']) ? 'Unknown' : $supportedoauth2array[$keyforsupportedoauth2array]['name'].($keyforprovider ? '-'.$keyforprovider : ''));
+					} else {
+						$OAUTH_SERVICENAME = 'Unknown';
+					}
 
 					require_once DOL_DOCUMENT_ROOT.'/includes/OAuth/bootstrap.php';