ext.ti.com has no MX records.
Question and response
Question
dig ext.ti.com. MX
Answer
The response has no answer records.
Authority
ext.ti.com. 300 SOA oqdibfd.itg.ti.com. hostmaster.ti.com. 2013107773 300 300 2419200 300
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0