ib.routit.net has no MX records.
Question and response
Question
dig ib.routit.net. MX
Answer
The response has no answer records.
Authority
ib.routit.net. 900 SOA auth01-peer.ib.routit.net. noc.routit.nl. 135 3600 1800 604800 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0