offtopic: rant about thoughtless enabling DMARC checks

[Michael A. Peters]

On 2/10/19 3:42 PM, Noel Butler via dovecot wrote:
> On 10/02/2019 12:49, Benny Pedersen via dovecot wrote:
> 
>>
>> fixing mailman will be the fail, solve it by letting opendkim and 
>> opendmarc not reject detected maillist will be solution,
> 
> 
> A general broad mailing list whitelist will be problematic, do work it 
> needs to look for specific list type hidden headers,  spammers and 
> nasties will incorporate those headers into their trash that 
> impersonates mailing lists and voila, they pass.

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