It's best to speak out your feelings for her if you meet her. Try to find out where she lives or get her phonenumber. Maybe the e-mail address you used was spelled wrong?
I'm gonna throw in my aggreance with these other folks.
But as a reply to the one advice to try and get her phone number or find out where she lives........
I gotta say, dont this is at all. If she's giving you no encouragement at this point, and you dont already have her number or address.......then you weren't meant to have it.
Getting this information on your own could have a negative impact on your goal.
If you were to do anything, although I think that letting go is the answer, but if you were to do something......I would say speak to one of the colleagues that she comes to see.
In a casual manner you can ask as to how she's doing, and thru them offer a message to her......but beyond that, I'd say just chill.
This seems to be very sensitive, I would say ya you should try to get some sort of closure but at the same time be carefull as not to be a wierdo.
I would not just let her go as weman sometimes play a bit hard to get but I would also not try to get her number or details on the sly.
If you are a patient hunter you can wait till you see her again and not be she but make an effort to get a momment to chat so you can reveal your feelings and see how she feels about it, and this should be even easier to do now that she has left your work place so any blunder will not affect your dailly life at work.
If she only comes round very seldomly then get to talking to someone who you know has her details and ask them to call her and either give your number to her or get her permission for you to use her number this way you have not offended her or forced yourself and invaded her privacy but you are meerly showing interest of future contact.
if she refuses or still ignores this attempt then throw in the towel as the next actions are borderline woiredo/ stalker
cheers and good luck