Copy and paste the text below into the default.asp page.
This will create a pop-up window which warns users who have unsupported browsers (IE6 or lower, Safari)

<%
' If the user is not logged in.
if "" & Session("USER")(USER_username) = "" then
%>
<script type="text/javascript">
// Check the Web Browser.
var msg = 'You are using ';
var status;
// Keys in this object must be the strings matched in the regex below.
// For each supported browser, specify:
//            title: String. Title of the browser
//            toonew: Number. Version at and above which a warning will be raised that the browser is too new to be supported
//            rec: Number. Lowest recommended version
//            min: OPTIONAL. Number. Lowest supported version
var supported_browsers = {
                'Firefox/': {'title': 'Firefox', 'toonew': 3.1, 'rec': 2.0},
                'MSIE ': {'title': 'Internet Explorer', 'toonew': 8.1, 'rec': 7.0}
                };
var browser_regex = new RegExp('(Firefox/|MSIE )([0-9.]+)').exec(navigator.userAgent);
if (browser_regex) {
                browser = browser_regex[1];
                version = parseFloat(browser_regex[2]);
                msg += supported_browsers[browser].title + String.fromCharCode(160) + version;
                if (version >= supported_browsers[browser].toonew) {
                                status = 'warning';
                                msg += ', which is newer than what we support.';
                } else if (version >= supported_browsers[browser].rec) {
                                status = 'pass';
                } else if (typeof supported_browsers[browser].min === 'number' && version >= supported_browsers[browser].min) {
                                status = 'warning';
                                msg += '. This is supported, but we recommend that you upgrade to a newer version.';
                } else {
                                status = 'fail';
                                msg += ', which is an unsupported version.';
                }
} else {
                status = 'fail';
                msg += 'a browser that is not supported.\nSome ANGEL functions (example, dropbox submissions) will not work correctly.\nThe supported browsers are Internet Explorer 7.0, 8.0 and Firefox 2.0, 3.0.'
                //msg += '\n' + navigator.userAgent;
}
if (status != 'pass') {
                setTimeout(function () { alert(msg); }, 1000);
}
</script>
<%
end if