Weird message from postfix when sending emails to @gmail

[BulleT]

Code:

This is the mail system at host phpqa.info.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<adrian.nitescu@gmail.com>: host gmail-smtp-in.l.google.com[209.85.220.47]
    said: 550-5.7.1 [86.122.121.252] The IP you're using to send mail is not
    authorized to 550-5.7.1 send email directly to our servers. Please use the
    SMTP relay at your 550-5.7.1 service provider instead. Learn more at
    550 5.7.1 http://mail.google.com/support/bin/answer.py?answer=10336
    7si4946767fxm.47 (in reply to end of DATA command)

86.122.121.252 is my IP the server has another one. I was trying to send via webmail. Why my IP appears there ? And how do I fix this ?

Thanks