Cannot connect to server using ERC

[Xue Fuqiao <xfq.free@gmail.com>]

I was trying to connect to irc.mozilla.org using ERC, but did not
succeed.  Here's my procedure:

  M-x erc RET
  IRC Server: irc.mozilla.org
  IRC Port: 6697
  Nickname: xfq
  Password: (blank)

But I _can_ connect it with Mibbit/Thunderbird.  I thought this is
because irc.mozilla.org uses SSL, but I still cannot connect to the
server after a `(require 'tls)'.  (I'm using OS X 10.8.3 and openssl is
installed on my system.)  Any ideas?

And here's the ERC buffer:
----------------------------------------------------------------------------------
|[Fri May 24 2013]
|
|
|Connection failed!  Re-establishing connection...                [18:55]
|
|
|
|[Fri May 24 2013]
|
|
|Connection failed!  Re-establishing connection...                [18:55]
|
|
|
|[Fri May 24 2013]
|
|
|Connection failed!  Re-establishing connection...                [18:55]
|
|
|
|[Fri May 24 2013]
|==> ERROR from irc.mozilla.org: Closing Link: [106.187.102.201] (Throttled:
|    Reconnecting too fast) -Email ircadmins@mozilla.org for more information.
|                                        [18:55]
|
|
|Connection failed!  Not re-establishing connection.
|
|
|*** ERC terminated: connection broken by remote peer
----------------------------------------------------------------------------------