Exchanger server problem.

Hello brothers,

We are using exchange server 2003 and fortinet router.
Everything is working fine. We can send and recive emails from out
side (Internally too). I open smtp port 25 on router. Everything’s
sounds good. Now the problem is we can not send emails to only YAHOO
though we can recive emails from yahoo. When i try to send mails to
yahoo, its giving me no errors and its not in the queue too. But its
not recieving in the YAHOO mail. I am so confused right now, for this
problem. Can any body tell me a solution for this problem, where to
look and what to do and all..?

Thanks in Advance.

Shafi Abdul.