diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index 0e58dbea059..b3718240543 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -931,11 +931,11 @@ def __init__(self, mailhost, fromaddr, toaddrs, subject,
         default is one second).
         """
         logging.Handler.__init__(self)
-        if isinstance(mailhost, tuple):
+        if isinstance(mailhost, (list, tuple)):
             self.mailhost, self.mailport = mailhost
         else:
             self.mailhost, self.mailport = mailhost, None
-        if isinstance(credentials, tuple):
+        if isinstance(credentials, (list, tuple)):
             self.username, self.password = credentials
         else:
             self.username = None