carnarychecker.com or canarychecker.com? (I'm only being nitpicky since it seems like an important detail in this case :-P )

Double checked, thanks for pointing out the typo, but I registered the correct one (phew):

Domain - canarychecker.com 1 year registration $12.00

I'm not entirely sure, but it seems like parsing the apache/nginx/other webserver access log is enough. When you detect request to some token ID, get email associated with it and send notification pre-recorded by the user.

If this is something you are willing to work on, send me an email, it is in my profile.