mx.bbox.fr has no TXT records.
Question and response
Question
dig mx.bbox.fr. TXT
Answer
The response has no answer records.
Authority
bbox.fr. 900 SOA primary.localdomain. dnsextmaster.bouyguestelecom.fr. 2012091938 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0