Ways of configuring mail redundancy and high availability


Two methods that can be used to create a redundant mail server environment. Depending on what you are trying to accomplish one of the two configurations outlined below will allow you to either set up your environment so no mail is lost if any downtime occurs, or so mail throughput has no downtime due to any server problems. Both of the configurations can be implemented together so as to obtain the desired affects in one environment.


The two approaches are:
1. Store Mail While Primary Server is Offline:
The article below, shows how to configure an MX record to have a backup MX.
Article ME020308
This will mean that if the primary mail server is offline, that the secondary backup MX will accept the e-mail on behalf of the primary.
To do this, configure the secondary MX mail server with all the domains to host, and use the smart host option for each domain, or in the SMTP service properties so that it is directed to the primary MX mail server. This way, if the primary goes offline, then the secondary will accept the mail, and queue it until the primary server is back online. This method does not allow users to access or send email, as the primary server is the only one with the authentication details and the stored email.
2. Server High Availability
For high availability MailEnable can run on two or more servers in a mail cluster, where all servers connect to shared storage for the configuration and email data. The software handles file locking so has the advantage of allowing all servers to run mail services at the same time. This can both allow load balancing and failover. This will also require a clustered IP address for any clients and other servers to connect to. There are many network load balancing switches available on the market that will do this. The MailEnable Enterprise Infrastructure Configuration Guide outlines this approach in detail.


How to configure back up or redundant mail servers:
Article ME020193

How to cluster MailEnable:
Article ME020023

Product:MailEnable (Ent-Any Ent-1.X Ent-2.X)
Class:TRB: Troubleshooting (Configuration or Environment)
Revised:Friday, May 31, 2019