3.3.8. MR RDATA format (EXPERIMENTAL)

    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    /                   NEWNAME                     /
    /                                               /
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

where:

NEWNAME         A <domain-name> which specifies a mailbox which is the
                proper rename of the specified mailbox.

MR records cause no additional section processing. The main use for MR is as a forwarding entry for a user who has moved to a different mailbox.