checks if string is valid email (bash function)

gistfile1.txt

# checks if string is valid email 

function isemail(){
  emailTest=$(echo "${1}" |  grep '^[a-zA-Z0-9._%+-]*@[a-zA-Z0-9]*[\.[a-zA-Z0-9]*]*[a-zA-Z0-9]$')
  if [[ "$emailTest" != "" ] ; then return 0; else return 1; fi
}