Javascript Email Validation

function checkEmail(mailstring)
{
var parsed = true;
var filter =/^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$/;
if (!filter.test(mailstring))
{
parsed=false;
}
return parsed;
}