Doing it on MX would require dnsbl lookups for each MX server in all
received mail.
That would massively increase amount of dnsbl lookups.
On 03.08.17 13:38, Martin Jiřička wrote:
I do not know if I would call it "massively". I already do
`reject_unknown_client_hostname` check and 4 other dnsbl lookups. So I
would do another 2 in addition to current 5? Yes, it is a lot, but
thats how it is… My server does not serve a huge amount of real mail
fortunately.
I'm not talking about DNS lookups, but about DNSBL lookups.
You ask each dnsbl for client IP, now you will ask them for each A or MX
record. That means, number of DNSBL lookups will increase ad least two times
(for each dnsbl you already query).
Note that some dnsbls require (payed) subscription if you use them too much.
you still can block them locally using the rules above.
I think it will not work, almost every spam comes from different domain.
we aren't talking about domains, but IP addresses of servers the domains
point to, correct?
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