smtpout02.voo.be has no MX records.
Question and response
Question
dig smtpout02.voo.be. MX
Answer
The response has no answer records.
Authority
voo.be. 2560 SOA brutele01.brutele.be. hostmaster.voo.be. 2026030500 16384 900 1048576 2560
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0