We fetch the common educational tlds and slds from publicsuffix.org.
See fetch_common_educational_tlds_and_slds.sh.
We fetch a list of known educational domains from github.com/Hipo/university-domains-list.
See fetch_known_educational_email_domains.sh.
We filter for only valid domains - domains that has a DNS A record.
See filter_valid_known_educational_email_domains.sh. Note that this may take some time.