Do i haveto put DNS in lan for my mail server

Are you using Google translate? Your question makes no sense in English. To run mail server you do need FQDN, static IP, MX record, and reverse DNS (authoritative DNS). IMHO small to medium size organizations should never run their own mail server unless they have some special security needs. I am having hard time seeing why would an individual run a mail server or for that matter authoritative DNS.
If i want to send mail directly with smtp in my lan i must have mx rr .in autortative dns server ? .Not caching server.