Our new ticketing site is now live! Using either this or the original site (both powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!
Trackernet is likely the system you are thinking of. It is not available externally unless connected to the TfL VPN (which is, as might be expected, staff only).
It’s also not 100% accurate for train numbers, I spent a week in one of the control rooms and it’s not used as an operational tool. It was however tremendously useful for identifying when the Circle Line trains would turn up.
We are aware of an issue with emails from the Forum to Microsoft-based email accounts (hotmail/outlook/live.com email addresses). This is being looked into currently, thanks for your patience meanwhile.