Hi there,
If I understand correctly, you want a definitive list of .edu domain names to compare users against to automatically approve them for your service?

The most authoritative list would be held by Educause - http://net.educause.edu/edudomain/index.asp but you won't necessarily be given the list. I would try dropping them an email anyway.

In the meantime, here are two other sources (but likely incomplete) that you could use.

1. https://github.com/Hipo/university-domains-list
2. http://pastebin.com/LND21t5F

If you'd like to discuss more, please schedule a call!
Best,
Neil