There are two principal ways to configure redundancy with MailEnable.

The simplest way to achieve redundancy is to install a copy of MailEnable as the master server. Then install separate copies of MailEnable on other servers and smart host the domains to the IP address of the master server. This will mean that if the master server is down, that the auxiliary servers will accept mail for the domains and hold it until it is online.

The DNS/MX settings for the domains will need to be changed in order to configure the appropriate MX preferences. Other mail servers learn about your mail server via DNS MX records. They are the means by which someone enumerates a target domain to the server responsible for receiving mail for that domain. MX records have a preference associated with them that determines the order in which they are used.

The lowest preference is attempted first. The lower the preference value, the higher the priority. Hence an MX record with a preference of 1 would be attempted before an MX entry with a preference of 10. More info on DNS and MX records is available at: https://www.mailenable.com/kb/content/article.asp?ID=ME020019

The above-mentioned approach is used if the backup mail servers are distributed in different geographic or logical locations.

A second alternative is to host all of the mail servers on the same local network and cluster the servers. This allows MailEnable to be installed on multiple servers and have them all use the same store for their messages and post office data. Any of these servers can then be used to access the mail. This requires that one of the servers share the mail data and configuration directories and that the others access them.