iRule to redirect to home page if URI contains email address

May be something like this. I have not tested it and used the regular expression that you have in question . If regular expression match redirect to some page. More on regexp can be found on.

https://devcentral.f5.com/articles/irules-101-10-regular-expressions

when HTTP_REQUEST {
    set uri [HTTP::uri]
    set result [regexp {[_A-Za-z0-9-\+]+(.[_A-Za-z0-9-]+)(@|\%40)[A-Za-z0-9-]+(.[A-Za-z0-9]+)(.[A-Za-z]{2,})} $uri]

    if($result)
    {
        HTTP::redirect "http://www.example.com/newlocation.html"

    }

}

Are you sure of your Apache rewrite rule? For it does not look like a redirect to me.

Also is an e-mail address the only thing expected in the query string?

It is better to illustrate your requirement with an example, for the sake of clarity.

Here's an alternative one based on what I thought you wanted:

when HTTP_REQUEST {
    if { [HTTP::query] ne "" } {
        if { [regexp {\y[^@]+@[\w.-]+\.\w+\y} [HTTP::query]] } {
            HTTP::redirect "/"
        }
    }
}