Exchange 2003 SMTP virtual server relaying

I would "really" appreciate any help on this.

There's a device sending alerts anonymously through the server to an external email address/domain. I just can't figure out why is that working.

On access control "anonymous access" is enabled of course.
As far as I know that means the server can receive email from any sender for local mailboxes but it doesn´t mean anyone can relay email through it. Is that correct ?

Under "grant or deny permissions to specific users or groups" authenticated users are granted submit and relay permissions. Remember, the device is not authenticating.

The device IP adress is not listed under "relay restrictions" with "only list below" checked.
It is though listed under "connection control" of course, otherwise it would not send any email. But that also shouldn't let it relay email thrugh the server.

Two last questions:

Do all this settings apply to MAPI users at all ?

What If I uncheck "Integrated windows authentication" or take the relay permissions to authenticated users under "grant or deny permissions to specific users.." ? will that prevent MAPI users to login, relay ?

Does "Allow all computer which sussefully authenticate to relay" mean that domaind joined computers will be granted relay permisions ?

Thanks a lot for any help.