Alternative to a million IF statements

A switch statement, as your code is only if-elses :-)

No, honestly. The best thing would be if you'd find a simple algorithm to create an email address from any given name, like

function mail(name) {
    return name.toLowerCase() + "@gmail.com";
}
var email = mail("Bob") // example usage

If they differ to much, you might use an object as a key-value-map:

var mails = {
    "Steve": "[email protected]",
    "Bob": "[email protected]",
    ...
}
var email = mails[name];

You could also combine those, if you have to determine which algorithm you need to use:

var map = [{
    algorithm: function(name) { return name+"@something"; },
    names: ["Steve", "Bob", ...]
},{
    algorithm: function(name) { return "info@"+name+".org"; },
    names: ["Mark", ...]
}];
for (var i=0; i<map.length; i++)
    if (map[i].names.indexOf(name) > -1) {
        var email = map[i].algorithm(name);
        break;
    }

or when it is a bit simpler:

var domains = {
    "gmail.com": ["Steve", "Bob", ...],
    "free.xxx": ["Mark", ...],
    ...
};
for (var domain in domains)
    if (domains[domain].indexOf(name) > -1)
        var email = name.toLowerCase()+"@"+domain;
        break;
    }

Just try to reduce the amount of data to deliver to the client as much as you can.

You can store all the email address in an associative array like

pseudo code

var emailsList = ["steve" => "[email protected]", "bob" => "[email protected]"];
then email = emailsList[name]; will solve your problem