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rustyx
Asked: 2014-03-04 07:31:30 +0800 CST

Precedence/co-existence of SPF and DKIM

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Is co-existence of SPF and DKIM specified somewhere (assuming the absence of DMARC)?

I want to put only my own IPs in the SPF and let 3rd parties send mail on behalf of my domain using DKIM.

What happens to e-mail that has a valid DKIM signature but fails SPF check (SPF FAIL)?

email

2 Answers

  1. Best Answer

    It depends entirely on how any given recipient has configured their mail server. Mine would refuse it outright because of the SPF failure, assuming you have -all at the end of your record (as you most certainly should). Someone else's mail server might do something completely different.

    SPF and DKIM are two completely separate systems; you cannot make up for a failure in one by an accomodation in the other.

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  2. You can control what will happen in this case with a email standard called DMARC.

    It gives you the option to specify whether you require both or either of the checks to fail, before the message is marked as spam. Of course this have to be supported by the receiving mail server, but almost all of the major services and most of the MTA software supports it so it's safe bet.

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