Use of MX Records

[Smith, William E., Jr.]

According to O'Reilly's 3rd Edition DNS & BIND book each host should hae at
least one MX record.  Furthermore, it suggests adding an MX record pointing
to itself.  Should this be the case for all hosts, even say a Windows box
which has no mail server, etc running on it.  Right now, we have 3 MX's
generated for each host.  Itself, and our two main mail servers.  Some here
have expressed concern over the use of MX records for workstations that
really don't need them since they aren't having mail delivered directly to
their box.  Just wondering if it's really necessary/optimal to add an MX for
each host, even though they may not really need it.  Insight would be
appreciated.

Thanks,

Bill Smith
<mailto:bill.smith at jhuapl.edu> 
The Johns Hopkins University                    Washington DC: 240-228-5523
Applied Physics Laboratory                      MD: 443-778-5523
11100 Johns Hopkins Road                        Fax: 443-778-5727
Laurel, MD 20723-6099                           Web:
<http://www.jhuapl.edu/>