How to setup smarthost for exhange server if there are 10 users.
Please tell me step to follow

Hmm... I'm not sure about the event sink, but I DO know that if you're doing this from a residential account, your ISP may be blocking port 25 going out to other networks. That's only if ALL your mail is getting stuck in the queue though, not just some of it.

It took me a while to figure out that's what was happening with my mail server. To fix it, I just set up my ISP's smtp server as a smarthost, with my login credentials. It worked pretty well for me, though some mail servers will only let you use the email address they gave you to send mail (Gmail, for example, if used as a smarthost, will only have the gmail address as the sender, even if you send it from a different address through your exchange server, if you set them up as your smart host).