Christopher Chan wrote: > Fajar Priyanto wrote: >> On Friday 04 January 2008 10:30:32 Ugo Bellavance wrote: >>>> AFAIK, redundancy for mail server seldom uses linux-ha/any other >>>> failover >>>> stuffs. It is most common to use 'backup MX' in DNS settings. So, when >>>> the main server in unreachable, the sender mail server would try to the >>>> secondary MX through DNS query. >>> That's the easy part, but where do you store the e-mail once you have >>> accepted it? If the pop/IMAP server is down for a while, people won't >>> be able to retreive their e-mail... >> >> The secondary MX will temporarily store the mails. And when the >> primary server is up again, it will get all the mail from the >> secondary. Yes. there will be a down time in terms of mail service for >> users. >> >> Maybe others can recommend a better best practice for this. > > Yes. No backup mx. You ought to have a cluster of mail servers to accept > mails for your domain if you need HA. Otherwise, let incoming emails > queue at their sending hosts as setting up a 'backup' mx that will only > hold the email and then pass them onto the 'primary' is really pointless > and only serves to 1) delay delivery of mail and 2) delay notification > of mail delay to the sending party. It is no longer acceptable today to > wait for a week before notifying the sender of non-delivery. The idea of > a backup mx no longer fits today's communications. I agree, and I don't want to have any client not being able to contact the pop/IMAP server for more than 15 minutes. Ugo