Here's some additional info:
Sometimes I get lucky and get a working server from the pool:
lucky working examples:
nc cluster3.eu.messagelabs.com 25
220 server-9.tower-123.messagelabs.com ESMTP
nc cluster3.eu.messagelabs.com 25
220 server-16.tower-90.messagelabs.com ESMTP
nc cluster3.eu.messagelabs.com 25
220 server-4.tower-90.messagelabs.com ESMTP
nc cluster3.eu.messagelabs.com 25
220 server-8.tower-125.messagelabs.com ESMTP
Best regards,
Alex