No new mail pop out notification when email sender is in the same network

[dexter]

Hi all,

I have this problem where I have no new mail pop out notification when I receive email sent by users of the same network where as I will have new mail pop out notification when i receive mail from an external sender.
May i know is there something wrong in my configuration that causes this or this problem already existed.
Any help is highly appreciated.

Thanks and Regards,
Dexter