+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ / MADNAME / / / +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:
MADNAME A <domain-name> which specifies a host which has a mail agent for the domain which will accept mail for forwarding to the domain.
MF records cause additional section processing which looks up an A type record corresponding to MADNAME.
MF is obsolete. See the definition of MX and [RFC-974] for details ofw the new scheme. The recommended policy for dealing with MD RRs found in a master file is to reject them, or to convert them to MX RRs with a preference of 10.