I am flabbergasted,....

Truly I am..
We needed to email one of my step-daughter's teachers. She lives with her mom and goes to school in a different state, but she had something come up with the school that would interfere with her summer visit with us, so we wanted some clarification and just needed to send off a quick email for details.
I asked her (16 years old now mind you..) for the address. She texted me back that the address (changed to protect the innocent) was smith.suzzie. That was it, nothing more. I wrote back asking for the rest of the address and she told me there was no more. If I simply put that in, it would get to her.
I have no idea where we went wrong. Do kids these days really not understand how email works?? They use it every day of their lives and don't really have a clue about it???
I have tried to explain to her via text this morning that, yes, that will work for her from within the school's server system, but that for me, from way outside their closed system, that won't work. She isn't getting it. She keeps telling me that it will work. Luckily, I'm smart enough that, now that I have the teacher's name, I can go to her school's website and get the rest of the information, but I foresee a nice long conversation this summer about how email and the internet in general really actually work...