Why can't I email myself at: MyEmail@74.125.235.55?

I opened cmd and typed ping gmail.com. It shows me:

C:\Windows\system32>ping gmail.comPinging gmail.com [74.125.235.55] with 32 bytes of data:Reply from 74.125.235.55: bytes=32 time=6ms TTL=56Reply from 74.125.235.55: bytes=32 time=6ms TTL=56Reply from 74.125.235.55: bytes=32 time=6ms TTL=56Reply from 74.125.235.55: bytes=32 time=215ms TTL=56Ping statistics for 74.125.235.55:    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),Approximate round trip times in milli-seconds:    Minimum = 6ms, Maximum = 215ms, Average = 58msC:\Windows\system32>

I have a Gmail account, so I emailed myself but instead of email@gmail.com I used email@74.125.235.55.

Response:

This is an automatically generated Delivery Status Notification

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

Delivery to the following recipient has been delayed:

xxxxxx@74.125.235.54

Message will be retried for 2 more day(s)

Technical details of temporary failure: The recipient server did not accept our requests to connect. Learn more athttp://mail.google.com/support/bin/answer.py?answer=7720 [74.125.235.54 (1): Connection refused]

----- Original message -----

MIME-Version: 1.0 Received: by 10.223.93.196 with SMTP id w4mr3261626fam.44.1309944998035; Wed, 06 Jul 2011 02:36:38 -0700 (PDT) Received: by 10.223.104.194 with HTTP; Wed, 6 Jul 2011 02:36:37 -0700 (PDT) Date: Wed, 6 Jul 2011 17:36:37 +0800 Message-ID: Subject: test From: Joseph To: xxxxxx@74.125.235.54 Content-Type: multipart/alternative; boundary=20cf3054a49348815504a763560c

testtest

I did not receive the email. Why?

Why can't I just substitute the gmail.com part with 74.125.235.55?