I've spent time today trying to configure SPF, DKIM and DMARC for my domain. Experience will determine how successful I have been. The next step is to configure my mail system, running Postfix, to check inbound mail using these mechanisms. Which tool do others prefer for this purpose? My DMARC record may be too strict; I essentially copied an example from http://www.zytrax.com/books/dns/ch9/dmarc.html (with a slight modification to change the address to which reports are sent). If necessary, I can switch to a "quarantine" rather than a "reject" policy for SPF, DKIM or both. Mailing list servers and their treatment of DKIM would be my main concern, although in such cases, if I understand rightly, the recipient should use the list server's DMARC record to determine the policy rather than mine, since it's the list server which is actually sending the mail out.