Short Description: Used to enable mail failover in a clustered environment.
Turns mail cluster failover routing on or off (Enables or disables Mail Router request failover). If users have replicas of mail files located on multiple servers, you can set this variable in the NOTES.INI file of all Lotus Domino servers in the domain to enable users to receive mail from servers within and outside the cluster when their home servers are down.
Valid Values are :
0 - Disables Mail Router request failover
1 - Enables Mail Router request failover
ND6 users please set this in the server/configuration document in the advanced tab of the router options and note that there are now 3 options for failover delivery. This is configured by Lotus Domino 6. Remove or comment out this setting in ND6.
MailClusterFailover=0 / 1
Server Configuration document - Router/SMTP-Advanced-Controls tab - Additional Controls section - Cluster failover
Domino 7 Performance Tuning Redbook
Redbook: Domino 7 Performance Tuning