export http_proxy='http://proxy.test.cz:1234/'

wget -nvq --proxy-user=test --proxy-password=test google.com &>/dev/null | grep -q '<H1>you cant't use internet</H1>' || ( echo "Proxy isnt't working" | mail -s "Proxy isnt't working!!!" -r "No-reply<no-reply@test.cz>" test@test.cz )