request !!!

[NYINYI]

Dear sir,


 I have got my send mail in localy.this is ok ?
( my local mail is berkeley at mmg.net.mm )
 
but I can´t send to external mail address.( berkeley_147 at yahoo.co.uk and NYINYI at mmg.com.mm )

I want to give my mail; send and receive from outside and wanna to test it ..
How can i do and configure at RedHat 9.0?
I think,My ISP haven´t filter SMTP .


Thanks in advance
NYINYI
MMG Technologies.