>* you did not provide a hint to the list-problem >* to "solve" the OP's problem DMARC is not needed
Mail admins need to get familiar with DMARC because major ISPs have begun to take this seriously in the past year and are starting to reject or put into spam folders when this is setup incorrectly or missing. Many mail servers trust inbound email better (not whitelist) when SPF and DKIM checks pass. Google is telling all of their mail customers to add DMARC DNS records to block spoofing of their own domains. Whether or not you agree with this Google recommendation, it's coming. I know this will cause problems with legit 3rd party senders and mailing lists. Many 3rd party senders are figuring out the proper way to send email. Something is going to have to be done on mailing lists or everyone will have to keep whitelisting them manually which is not a good long-term solution. https://blog.returnpath.com/how-to-explain-dmarc-in-plain-english/ https://support.sendgrid.com/hc/en-us/articles/200182958-Everything-about-DMARC- >you can simply reject based on the from header anything pretending it's >you own domain from foreign servers - no need for DKIM/DMARC/SPF - and >on the MTA level but there are not only mailing-lists - not everyone can block their own domain at the MTA level but they can setup DKIM/DMARC/SPF - this does not cover bad senders spoofing your domain to other mail servers not under your control.
