Redirect and append URI

Please try this:

when HTTP_REQUEST {
    if { [string tolower [HTTP::host]] equals "www.mmicagent.com" } {
        HTTP::redirect "http://www.motoristsmutual.com/map/ouragents/mmicagent[HTTP::uri]"
    }
}

This will append whatever URI the client specifies to the end of the redirect URL.