> There's evidence that some spammers reverse-sort MX records, > intentionally sending to the backup MX first. Consequently, the > backup MX /must/ have anti-spam controls identical to the primary. > > But consider if you truly need a backup MX. Most folks have dropped > them because they're spam magnets, and reliability has increased > such that extended down time is unusual. Nearly all legit mail > servers will retry delivery for several days if your MX is down. > > As a compromise, some folks keep a "hot spare MX" mail server > configured as backup MX but with port 25 firewalled off until the > primary fails.
hi, thanks for your reply. I need an mx-backup because my first server could goes down. So, I follow your advices installing antispam on mx-backup. Pol
