7/3     If FOO is mx 0ed to BAR and BAR is mx 10ed to BAZ, but FOO is MX10ed
        to QUUX, where will mail for FOO go when BAR is down?  BAZ or QUUX?
        BAZ I assume, but it is legal to have the pointer to QUUX?
        \_ Mail will go to QUUX, think about it.
        \_ One things to note, MX records are not recursive.