The message has actually been sent this time, here's the except from maillog:
Dec 9 05:40:45 bugzilla sendmail[7723]: mB9Aeiqq007723: to=info@kobaltwit.be, ctladdr=bugzilla-daemon@openvz.org (48/48), delay=00:00:01, xdelay=00:00:00, mailer=relay, pri=31325, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (mB9AejRv007730 Message accepted for delivery)
Dec 9 05:41:06 bugzilla sendmail[7732]: mB9AejRv007730: to=<info@kobaltwit.be>, delay=00:00:21, xdelay=00:00:21, mailer=esmtp, pri=121661, relay=asav01.bru.nucleus.be. [195.207.48.21], dsn=4.0.0, stat=Deferred: 451 4.7.0 try again later #552 (kB8Bew028464378600)
Dec 9 06:18:12 bugzilla sendmail[15825]: mB9AejRv007730: to=<info@kobaltwit.be>, delay=00:37:27, xdelay=00:00:06, mailer=esmtp, pri=211661, relay=asav01.bru.nucleus.be. [195.207.48.21], dsn=2.0.0, stat=Sent (2.0.0 message kB8CIA0284646858SY accepted #554 (kB8CI6028464685800))
You probably need to check you Spam/Junk folder...