On 3/13/2014 8:42 AM, Pol Hallen wrote: > Hi all, I need an advice about my mx-backup server > > main mail server has many antispam system (amavis, spamassassin, etc.), > when an email bounced by these antispam, the email goes to mx-backup > server. mx-backup server keep email inside own queue. > > So, do I need install amavis and other antispam system also on mx-backup? > > thanks for help! > > Pol >
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. -- Noel Jones
