In that case I believe the last thing cos it can't take this particular domain name over 2 hours, when it take no-ip changes to take affect like 30 seconds later.
btw it can't be that either since work isn't using the same dns servers
Feb 5 21:45:00 localhost sendmail[13512]: n15Kj0OK013512: from=<xx.xx@bahnhof.se>, size=1138, class=0, nrcpts=0, proto=ESMTP, daemon=MTA, relay=mx6.bahnhof.se [213.80.101.16]