Regular expression to find government domains for websites / email addresses

regex.rb

# regex to match government emails. Should detect:
# foo.gov, foo.mil
# foo.gov.uk, foo.mil.uk
# foo.fed.us
# foo.govt.nz, foo.gc.ca, foo.guv.ro, gub.uy
# note: foo.gouvt, foo.gc, foo.fed.uk, etc. will technically pass, but they are invalid domains
regex = /(\.g[ou]{1,2}(v|b|vt)|\.mil|\.gc|\.fed)(\.[a-z]{2})?$/i