Most people use their internet proveder as their EMail address ... this is a bad idea, as if you move, or change your internet provider, you lose that EMail address.
Yahoo Mail is probably one of the best choices.
When making an EMail address name, and a Username & Password, it is best to think long and hard about the choice of a name, overnight ... As no one wants to be known as QWERTYUIOP, with a password of 012345678910.
Write down your EMail address, and UN & PW, Trainz disc registration key code on each Trainz disc box, on a piece of masking tape ... then you will never lose the information.
Always use the same UN & Password, as well as the same EMail address on all your different versions of Trainz.
Keep a hand written log book of all your important Trainz, and PC information ... Did you ever lose a cell phone, and lost all your contacts phone numbers. Have you ever had a PC HD fail, and all your stuff is not backed up on another PC, Disc, Flash Drive, External HD ? Fail to plan ... plan to fail !