Hosting an Email server and receiving all mails pertaining to @mysite.com

I have question regarding emails sent/received by any website out there.
Assuming its mysite.com. Everyuser will be
getting an email address say something like j...@mysite.com. Any
person using the same website or any other website or any one on the
planet can send an email to j...@mysite.com and for jack there is a
Inbox feature built into his dashboard, where he will be seeing all
these emails(forget about jack sending emails to anyone, now). So to
achieve this, I have changed MX records of my site(in godaddy) to:
Priority:10
Host:@
Goes To:www.mysite.com.

And the MX records lookup says:
;; ANSWER SECTION:
www.mysite.com. 3600 IN CNAME mysite.com.
mysite.com. 604800 IN MX 10 www.mysite.com.

And I have configured postfix on my production machine(www.mysite.com
server) to receive all mails. Even then its not receiving any emails
(all getting bounced). May I know whats happening? So MX records is the only one which will be responsible for any screwups? I have tried many sites like stackoverflow but
didn't receive any help. Please help me.