We have an exchange server 2003 sp2, some of our users didn't recieve email from specific sender but others recievedbut exchange said that the message deliverd but outlook didn't reciev it. I check both our Exchange server and Symantec for exchange and they didn't block the sender.

If you traced the email, and it says it delivered it to everyone, then it most likely did. Do the people that "Didn't Get it" have rules that would move the e-mail to another folder perhaps? (I have seen this one hundreds of times) Also, I would check the deleted items and recovery bin of people thatdon't think they got it to ensure it was not thrown away.