offtopic: rant about thoughtless enabling DMARC checks

Noel Butler noel.butler at
Mon Feb 11 02:01:41 EET 2019

On 11/02/2019 09:46, Michael A. Peters via dovecot wrote:

> However the majority of spammers do not spam with a properly configured 
> Reverse DNS - so detect the list header >and skip DMARC if list headers 
> are present AND Reverse DNS matched the HELO/EHLO

A hell of a lot do, though (this is pretty average percentages here)

Accepted 70.07%
Rejected  29.93%
Total      100.00%

5xx Reject relay denied 4.27%
5xx Reject unknown user 7.93%
5xx Reject sender address 7.32%
5xx Reject unknown client host 52.44%
5xx Reject RBL 3.66%
5xx Reject milter 24.39%
Total 5xx Rejects 100.00%

unknown client host was high as 95% up till about 10 years ago, so they 
are slowly learning.

Kind Regards,

Noel Butler

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