[CentOS] Mail from domain problem

[Barry Brimer]

> Hi,
>
>    I installed a CentOS 4.7 server, the system information is:
>
> # cat /etc/sysconfig/network
> NETWORKING=yes
> HOSTNAME=mail.domain11.com
>
> # hostname
> mail.domain11.com
>
> #echo "test " | mail -s "test mail" someone at domain22.com
>
> I would like to receive mail is root at domain11.com, but I received is root at mail.domain11.com
>
>
>
> How to correct it?
>
> (I've tested there is no problem in CentOS 5.2)
>
> Best regards

What MTA are you using?  Sendmail?  Postfix?  Exim?  Qmail?  Courier?