Closes #22646: Accept list as well as tuple to support initialisation via dictConfig().

Lib/logging/handlers.py

@@ -931,11 +931,11 @@ class SMTPHandler(logging.Handler):
         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