ahmedsa
They will conflict if they have the same domain name & external DNS records are configured to resolve that domain to both servers, which theoretically should not be the case.
In practise you would point the external DNS records at the second server so that the domain name resolves correctly to only one server ie the sme8.1 server.
If you prefer you can rename the domain on the first server to avoid confusion, but it should not be necessary.
Also you could disable mail services on the first server, but that will stop system mails to admin, also it should not be necessary.
You need to explain your situation better, eg where are the 2 servers located & so on.