That would be correct. $address will hold the [email]userid@host[/email] part, and $fulladdress will hold the full nick!userid@host.

You can then use $mask (qv) to do the masking of the $fulladdress: $mask($fulladdress,2)

I assume that you have each command on a separate line, too, rather than all on the one line:

Code:
on *:text:*:?: {
  var %s.chan = #chat 
  if ($nick !ison %s.chan && $me isop %s.chan) {
    var %nick.addr = $mask($fulladdress,2)
    var %cnt = $nick(%s.chan,0) 
    while (%cnt) {
      if ($address($nick(%s.chan,%cnt),2) == %nick.addr) {
        ban -ku3600 %s.chan $nick(%s.chan,%cnt) 2 Relay Spammer Detected 
      } 
      dec %cnt 
    } 
  }
}

Sais