My internal DNS has the same zone as my external company.com.au for both, I have setup a SPF record externally but for internal servers I believe they won't go looking that far if the internal DNS doesn't report one is that correct?
If the above is true then I believe I need to setup an internal SPF record to stop emails being spoofed to look like they come from an internal sender. I was wondering what exactly an internal SPF record would require i.e. can it just hold our external
delivery system (Trend HES) the same as our external SPF or would it also need the internal networks exchange servers. If an internal SPF does require the internal servers then does it need them in both dns name and IP's or would the IP range of all
our internal sites be sufficient?