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.

Will it replace 'www.mmicagent.com' with 'www.motoristsmutual.com/map/ouragents/ mmicagent' and append '/fasih' which was originally part of the orignal URI

Yes. If the request is for www.mmicagent.com, the user will be redirected to www.motoristsmutual.com. Any URI that is in the original request will get appended to the end of the redirect URI.