Zitat von Binarus via Info-cyrus <info-cyrus@xxxxxxxxxxxxxxxxxxxx>:
Combine SPF / DKIM with domain blacklisting, and then you *have* an efficient spam fighting tool.
As stated the spam actually reaching our inboxes after around 90% cutoff is valid DKIM/SPF signed as it is mostly from the big free providers like Outlook.com, Google and Yahoo. Some other big share is from professional spam farms with always alternating IP and Domains ranges from all over the world with also valid DKIM/SPF. Next big share is from educational servers also mostly valid DKIM/SPF. The tiny rest with around 10% is in fact not DKIM/SPF signed. From the valid e-mail around 20% looks like having a valid SPF/DKIM, mostly professional newsletters not personal mail from customers.
So No, SPF/DKIM is no useful spam fighting tool at least not in our corner of the world.
Regards Andreas
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