Mails are bounced even though proper mx record has been set

You probably don't own example.com.

I hope that helps.

I have replace the domain name.

Most of the helpers around the forum and IRC channel don't like supporting users who eradicate this information. It's makes it harder to diagnose, especially in cases like mail.

Oh, I am sorry, I should have mentioned it before.

Then why post saying you're sorry and instead just give rnowak the information? Heh.

Based on the information you've provided, I can only conclude that your mail server has been eaten by a grue. After all, this would fit your provided information of "my mail server doesn't work but I won't give any information that could be used to identify the problem, why doesn't it work?"

Asking this sort of question while refusing to provide any information just wastes our time.