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	The mailbox encoding standard assumes a mailbox name of the
	form "<local-part>@<mail-domain>".  .....

	The DNS encodes the <local-part> as a single label, and
	encodes <mail-domain> as a domain name.  The single label from
	the <local-part> is prefaced to the domain name from
	<mail-domain> to form the domain name corresponding to the
	mailbox.  Thus the mailbox HOSTMASTER at SRI-NIC.ARPA is mapped
	into the domain name HOSTMASTER.SRI-NIC.ARPA.  If
	the<local-part> contains dots or other special characters, its
	representation in a master file will require the use of
	backslash quoting to ensure that the domain name is properly
	encoded.  For example, the mailbox Action.domains at ISI.EDU
	would be represented as Action\.domains.ISI.EDU.