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Should I be concerned about an spf include that uses "?all" as its final statement?

Last Modified: 2019-02-20
The organization that I work for uses outside firms to conduct email-based surveying and research. We're also hit constantly with phishing attempts and have worked to make sure our users understand that official emails will always come from our domain.

A research firm that I have been recently working with sent me the SPF record they maintain for their clients to include in their own SPF records to allow the firm's servers to send emails on behalf of their domains. However, when I checked the SPF record they want me to include I noticed that it has several includes of its own. When I checked those out, I found that one of the includes ends with "?all". I checked to make sure it would neutral-mark every email by sending myself a spoofed email using research firm's domain and an unsecured smtp sever, and it worked.

Obviously I don't want to include "?all" in my SPF record because it would (seemingly) undo any good the record was doing to begin with. It's not hard to check SPF records, and wouldn't take an attacker long to figure out they could send emails as my domain.

Am I being dense here? The vendor with the "?all" in their SPF record is a nationwide leader in providing survey logistics, and is extremely widely used; I can't imagine that I'm the only customer with concerns about this practice. Is using "?all" more common/reasonable than my understanding of it?
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KimputerIT Manager

I actually have no idea why they would add it. It serves no purpose. Officially, the thinking behind it from RFC4408 is:

The domain owner has explicitly stated that he cannot or does not
   want to assert whether or not the IP address is authorized.  A
   "Neutral" result MUST be treated exactly like the "None" result; the
   distinction exists only for informational purposes.

You made an effort to add this records, only to have it do nothing. From a more logical standpoint (mine at least, apparently yours too), I'd say that was wasted energy.

I can only think of that the firms with ?all SPF records are still not sure if they have all the IP's listed correctly, and don't want to risk blocking legitimate emails from some forgotten but important server.
acanalystsSystems Analyst


Thanks for the context from RFC4408; that makes explicit what I was already assuming.

I would think the research firm would follow the SPF Council's suggestion that "~all" be used until "-all" can be implemented, though I do know that can be a little heavy-handed. Still, "?all" seems to fall under the SPF Council's characterization of "+all":
The domain owner thinks that SPF is useless and/or doesn't care.
Systems Analyst
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