Sendmail local and external mail

[Ved Linux]

Hi,

We have 2 sendmail server working.

But when any user want to send mail to local user he can not use the address like user2 at mycompany.co
m because than the mail will go to the mail server (mail.mycompany.com) can not deliver the mail
locally.

One has to send it like "user" only without any sufix.

So all user need to have only userx,usery..... a/c in their address book so they can use the local
mail.

And when  ever the internet link is not working the local mail can not delivered if the mail sent
thru user at mycompany.com.

HOW it is possible to user the same address like user at mycompany.com even if any user is local then
mail can be delivered locally.

Thanx,

NV