For me, I get a black telnet session for a long time, then eventually it throws up this:
220-hermes.hosts.co.uk ESMTP Exim
220 Spamming and unauthorised relaying not allowed
554 SMTP synchronization error
Connection to host lost.
C:\>
That probably means they are trying to do some kind of check to confirm whether you are valid or not and cannot.
Not really a lot you can do. If you are trying to email someone who uses that service provider (Namesco) then they need to contact them to find out what is happening.
-M