diff -r 72a8446fdf9a Lib/smtplib.py
--- a/Lib/smtplib.py	Mon Mar 18 15:04:33 2013 -0700
+++ b/Lib/smtplib.py	Sat Apr 13 12:06:47 2013 -0400
@@ -66,7 +66,7 @@
 OLDSTYLE_AUTH = re.compile(r"auth=(.*)", re.I)
 
 # Exception classes used by this module.
-class SMTPException(Exception):
+class SMTPException(IOError):
     """Base class for all exceptions raised by this module."""
 
 class SMTPServerDisconnected(SMTPException):
@@ -221,8 +221,9 @@
 
         If specified, `host' is the name of the remote host to which to
         connect.  If specified, `port' specifies the port to which to connect.
-        By default, smtplib.SMTP_PORT is used.  An SMTPConnectError is raised
-        if the specified `host' doesn't respond correctly.  If specified,
+        By default, smtplib.SMTP_PORT is used.  An IOError is raised if the
+        connection to the `host` fails. SMTPConnectError, a subclass of
+        IOError, is raised for protocol-level errors. If specified,
         `local_hostname` is used as the FQDN of the local host.  By default,
         the local hostname is found using socket.getfqdn(). The
         `source_address` parameter takes a 2-tuple (host, port) for the socket