Pool selection based on header

Vitaliy is right on the money I think. The following isn't perfect, but should get you in the right direction.

when HTTP_REQUEST {

    set whereis [whereis [IP::client_addr] country]

    switch [string tolower [HTTP::host]] {
        "mail.sunrise.com" {
            if { $whereis equals "GB" } {
                pool example
            } else {
                HTTP::redirect "http://sunrise.com"
            }
        }
        "www.sunrise.com" -
        "sunrise.com" {
            if { ( $whereis equals "US" ) or ($whereis equals "IN" ) } {
                pool sunrise
            } else {
                drop
            }
        }
    }
}