Have a MailStation to play with and set up or a customer.... Here's an NMAP taken of it after downloading email. Too lazy to sniff it.
Starting nmap V. 2.3BETA5 by Fyodor (email@example.com, www.insecure.org/nmap/)
No ports open for host xxx.foo.net (xx.xxx.xx.xxx)
Nmap run completed -- 1 IP address (1 host up) scanned in 258 seconds
Oh well...No open ports. Anyone any closer on the checksum.
PS: ftp.cidco.com is interesting. Big mailing lists anonymously online. Hmmm....