[Discuss] DMARC, SPF, DKIM

[Edward Ned Harvey (blu)]

Because I'm pretty sure there's a relatively high concentration of people here who maintain their own mail servers, I want to bring this up as an often overlooked practice you should be following:

It is advisable to use DMARC (https://dmarc.org/), in addition to SPF and/or DKIM. DMARC addresses common problems of SPF and DKIM; specifically, DMARC was created because so many domains have SPF and DKIM misconfigured, resulting in recipient mail servers often ignoring the SPF and DKIM failures.

Utilizing *all* SPF, DKIM, and DMARC, yields the highest confidence threshold, and best result.

>From http://www.mcafee.com/us/resources/solution-briefs/sb-spf-dkim-dmarc-demystified.pdf

"using DMARC feedback, an organization may determine that there are valid IP ranges that are not included in their SPF records, allowing them to update the records and increase the accuracy of their DMARC posture."