> On Jun 16, 2016, at 7:54 AM, Merijn van den Kroonenberg <mer...@web2all.nl> > wrote: > >> Agreed. >> >> We use sendmail, and check our DNSBL's their, it is much more efficient to >> use them before we ever engage SA. It is extremely rare to find an IP that >> lands on a reputable DNSBL and in those cases we can whitelist. Of course >> most of our traffic is B2B, not sure how effective this would be in B2C or >> C2C. > > What do you use in sendmail to check the blacklists? > > And do you use scoring or just direct block when on a BL? > > >
I simply reject when an IP address is on a BL. no questions asked. I also reject if the host fails its reverse lookup. In cases where a vendor or customer has a misconfigured email server, we can whitelist and notify them. I've actually helped several of our customers who were having issues with their clients resolve bad configurations. The problem lies in that I have come across more than a few SPAM mail filtering services that don't have correct configuration (i.e things like reverse lookup identify a different host). A more nefarious case I've run across is that a mail filtering services charging on a per outbound email, so clients are using the service for inbound, but than use their own MTA to send (bypassing the ISPs) so they don't get charged. Again, our servers only deal with B2B, not sure of the impact in B2C/C2C. SA is processes intensive, if you're looking to save CPU time, using BLs at the MTA process level is much faster (IMHO).
