function CheckValidEmail(checkThisEmail)
{
var myEMailIsValid = true;
var myAtSymbolAt = checkThisEmail.indexOf('@');
var myLastDotAt = checkThisEmail.lastIndexOf('.');
var mySpaceAt = checkThisEmail.indexOf(' ');
var myLength = checkThisEmail.length;

if (myAtSymbolAt < 1 ) 
 {myEMailIsValid = false}

// at least one . (dot) afer the @ is required
// x@yellow : NOT valid
// x.y@yellow : NOT valid
// x@yellow.org : VALID

if (myLastDotAt < myAtSymbolAt) 
 {myEMailIsValid = false}

// at least two characters [com, uk, fr, ...] must occur after the last . (dot)
// x.y@yellow. : NOT valid
// x.y@yellow.a : NOT valid
// x.y@yellow.ca : VALID

if (myLength - myLastDotAt <= 2) 
 {myEMailIsValid = false}

// no empty space " " is permitted (one may trim the email)
// x.y@yell ow.com : NOT valid

if (mySpaceAt != -1) 
 {myEMailIsValid = false}

//--------------------------------------------------------------------------------------------------------

// .xy@yellow.a : NOT valid

if (checkThisEmail.indexOf(".") == 0)
 {myEMailIsValid = false}

// xy.@yellow.a : NOT valid

if (checkThisEmail.substr(checkThisEmail.indexOf('@')-1,1) == ".")
 {myEMailIsValid = false}

// xy@.yellow.a : NOT valid

if (checkThisEmail.substr(checkThisEmail.indexOf('@')+1,1) == ".")
 {myEMailIsValid = false}

//--------------------------------------------------------------------------------------------------------

if(!myEMailIsValid) { alert("Email Address is INVALID!"); }
return myEMailIsValid
}