Thanks for all the help. BTW, is spamassassin still a popular option for antispam today? or should I use rspamd instead?
Regards. On Wed, Apr 10, 2024 at 10:23 PM Bill Cole via Postfix-users < postfix-users@postfix.org> wrote: > On 2024-04-10 at 05:46:36 UTC-0400 (Wed, 10 Apr 2024 17:46:36 +0800) > Mr. Peng via Postfix-users <vir...@gmail.com> > is rumored to have said: > > > I have been using spamhaus, spamcop, sorbs as the RBL providers for > > antispam. > > But some of the customers speak to me about the FP issues caused by RBL. > > Do you think the three RBL above are reliable in a practical system? > > Those are three of the best, but you have to understand that they are > complicated and may not fit YOUR needs. > > Spamhaus offers multiple DNSBLs which each has a vey specific definition, > which they aggregate in the "Zen" list which uses reply value to indicate > which component an address listing belongs to. Not all component lists of > Zen are appropriate for all MTAs. Spamhaus is extremely careful about > making each list reliably represent what they claim it represents. They act > quickly on the rare occasions when they inadvertently list sources of > legitimate email. > > SpamCop is based on actual feeds of spam from many sources, and when they > list an IP, you can be certain that it recently sent spam. They do not > exempt major mailbox providers who are also major spam emitters. If you use > the SpamCop list as an absolute test, you will reject some legitimate mail > which shares an outbound MTAQ with spam. Reliably. > > SORBS is also informed by multiple sources of spam, and like SpamCop they > do not exempt mixed sources. Like Spamhaus, they have both independent > DNSBLs and an aggregated list that uses distinct return values for each > component list, so you need to take that into account when using it, to fit > the different sorts of listings to different interfaces. Like SpamCop, some > of the SORBS components intermittently list major mixed sources. > > You really need to look at your DNSBL choices carefully and with an > understanding of your users and their needs. You may want to consider using > them in a more complex filtering tool like SpamAssassin where it is > possible to weight the impact of different DNSBLs to fit your needs and to > make explicit direct exemptions if you like. > > -- > Bill Cole > b...@scconsult.com or billc...@apache.org > (AKA @grumpybozo and many *@billmail.scconsult.com addresses) > Not Currently Available For Hire > _______________________________________________ > Postfix-users mailing list -- postfix-users@postfix.org > To unsubscribe send an email to postfix-users-le...@postfix.org >
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