diff -r 226d6c1485e9 Doc/library/smtpd.rst
--- a/Doc/library/smtpd.rst	Sun Aug 07 20:20:33 2016 -0700
+++ b/Doc/library/smtpd.rst	Mon Aug 08 16:06:38 2016 +0530
@@ -32,9 +32,10 @@
                       map=None, enable_SMTPUTF8=False, decode_data=False)
 
    Create a new :class:`SMTPServer` object, which binds to local address
-   *localaddr*.  It will treat *remoteaddr* as an upstream SMTP relayer.  It
-   inherits from :class:`asyncore.dispatcher`, and so will insert itself into
-   :mod:`asyncore`'s event loop on instantiation.
+   *localaddr*.  It will treat *remoteaddr* as an upstream SMTP relayer.  Both
+   the parameters *localaddr* and *remoteaddr* should be a tuple in form ``("host",portnumber)``,
+   where *host* is a valid IP/FQDN.  The object inherits from :class:`asyncore.dispatcher`,
+   and so will insert itself into :mod:`asyncore`'s event loop on instantiation.
 
    *data_size_limit* specifies the maximum number of bytes that will be
    accepted in a ``DATA`` command.  A value of ``None`` or ``0`` means no