On Thu, Dec 18, 2008 at 2:46 PM, Terry Carmen <te...@cnysupport.com> wrote: > > DJ Lucas wrote: >> >> Hi guys, I believe that I already have the answer to this pretty basic >> setup, but I just wanted to do a quick sanity check. >> >> I'm setting up a backup MX, and for one of the domains that it will relay >> to, it should do no filtering whatsoever as there is a Symantec device in >> front of the primary. The device is configured with a catch-all, and I have >> verified that no backscatter is generated when sending to an invalid >> address, and the admin of that server wants to review everything coming at >> him. > > The backup should have the same filtering as the primary, since a lot of > spammers use it without every trying the primary, specifically because a lot > of people implement the backup without filtering. >
yes, you need to have equivalent controls at all mxes. much spam will come directly to the backup mx, and your backup mx will greatly reduce the abilities of the primary site's filtering. for instance, RBL checks, greylisting, etc will no longer be effective for the primary because mail is coming from your backup MX. this is why spammers often just send straight to the second or last MX, hoping for the configuration the OP is proposing.
