Improve email validation

func/main.sh

@@ -612,7 +612,7 @@ is_dns_record_format_valid() {
 
 # Email format validator
 is_email_format_valid() {
-    if [[ ! "$1" =~ "@" ]] ; then
+    if [[ ! "$1" =~ ^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,63}$ ]] ; then
         check_result $E_INVALID "invalid email format :: $1"
     fi
 }