On 12/14/19 4:29 PM, Keith Seyffarth wrote: > Grant Taylor via Mailman-Users <mailman-users@python.org> writes: > >> On 12/13/19 9:02 PM, Mark Sapiro wrote: >>> As postgrey learns, it will remember triplets (sender, sending IP, >>> recipient) and not delay them and in addition will whitelist domains >>> that retry successfully more than a few times. >> The bigger senders are doing things now (more than ever) that they >> weren't doing 15+ years ago. Now farms of servers will try to contact >> you. The message may first try from one IP, then from another IP, then >> from a 3rd.... It may eventually try from the same IP and make it through. >> >> I think most grey list solutions have an option to specify the network >> (frequently configured a a /24) for the sending IP. This significantly >> helps with different servers in the same server farm trying to resend >> messages. > Some greylisting solutions also allow you to whitelist a domain or > subdomain, but this can result in spammers spoofing that domain getting > through... > > Keith > > Unless you only whitelist domains which use SPF, then SPF will catch the spoofers.
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