[Exim] Second MX

Hello

I have exim 3.35 TLS and I want to put second MX.
I know, that one should to make such registrations:
IN MX 10 mx1.Domain.Com
IN MX 20 mx2.Domain.Com
The whole of postal accounts is on MX1, MX2 it has to keep rank when MX1 is been overburdened with .
Someone link knows or maybe me to spread configurations on MX2???

I greet
Roxik