# Matching a valid e-mail address[ A-z 0-9 and -,.,_,@ ] - no blank spaces
# Allow IP addresses to included into the e-mail address
# check_email_address ( $e-mail )
sub check_email_address {
    $email = $_[0];

    # If the e-mail address contains:
    if ( $email =~ /(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/
      || $email !~ /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/ )
    {
        return 0;
    }

    else {

        # Return a true value, e-mail verification passed.
        return 1;
    }
}