scom email notification

hi 

i am trying to configure send email notification  in scom 2007 R2

and i want to test it 

i have created smtp channel and subscriber and subscription

i have configured a hub transport to receive smtp traffic from scom and i tested this by sending an smtp email from powershell and things worked fine.

to test the email notification i have installed notifications test tool . when i run it noting is received in the client mailbox

please i need help to know what i am missing

is there any specific configuration to the sender account or returnaddress ??

Thanks in advance