Re: no external relay found, skipping DMARC check

On 2024-10-14 at 04:42:28 UTC-0400 (Mon, 14 Oct 2024 10:42:28 +0200)
Gregory Colpart via users <[email protected]>
is rumored to have said:

> Hello,
>
> I try to use Mail::SpamAssassin::Plugin::DMARC with SpamAssassin 4.0.0
>
> I installed Perl dependencies.
>
> But I fail to have DMARC check, I have this debug message:
>
> Oct 14 09:47:45.091 [1486800] dbg: DMARC: using Mail::DMARC::PurePerl 
> for DMARC checks
> Oct 14 09:47:45.091 [1486800] dbg: DMARC: no external relay found, 
> skipping DMARC check
>
> What is "external relay"?

A mail source which is not under the control of the entity managing the 
SpamAssassin instance.

SpamAssassin has configuration parameters that are used to determine the 
status of SMTP clients: internal_networks, trusted_networks, and 
msa_networks. These are documented internally (run  'perldoc 
Mail::SpamAssassin::Conf' )  and at 
https://spamassassin.apache.org/full/4.0.x/doc/Mail_SpamAssassin_Conf.html 
with additional discussion at:

https://cwiki.apache.org/confluence/display/SPAMASSASSIN/TrustPath
https://cwiki.apache.org/confluence/display/SPAMASSASSIN/ImportantInitialConfigItems

SpamAssassin uses the "Received" headers of a message to determine the 
transport path of mail. Whatever mechanism you use to pass messages to 
SA for scanning must include & preserve all Received headers (*including 
the latest one showing local receipt*). Without the full set, SA cannot 
detect which relay step to use for SPF checking.

> How to enable DMARC check?

Configure SpamAssassin properly and let it examine non-local mail.




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Bill Cole
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