Start/notes.ini Parameters/MailClusterFailover

MailClusterFailover

Parameter: MailClusterFailover
Short description: Controls whether the Notes client switches automatically to a cluster mate when the home server is unreachable for mail. Important parameter for HA scenarios with mail.

Profile

Parameter
MailClusterFailover
Category
Cluster
Component
Server
Available since
9.0.1 (and earlier)
Supported versions
9.0.1, 10.0, 11.0, 12.0, 14.0, 14.5, 14.5.1
GUI equivalent
Configuration document → Router/SMTP → Advanced → Controls → Cluster failover
Possible values
0 = off • 1 = on

Description

MailClusterFailover controls mail router cluster failover in a Domino cluster environment. If a recipient's home mail server is temporarily unreachable, the Router task with failover enabled automatically forwards the incoming message to a cluster replica of the mail file on another available cluster member. As soon as the original home server is running again, the cluster replicators sync the delivered messages back to the home server.
Prerequisites for effective failover are:
  • the participating servers are members of the same Domino cluster,
  • the recipient's mail file is replicated on at least two cluster members,
  • the cluster replicator (clrepl) is running on the participating servers.
The parameter complements — but does not replace — the database-side cluster failover for active client connections (Server_Cluster_* family). It only affects the mail routing path of the Router task.

Example configuration

Enable mail router cluster failover (typical default value in cluster environments):
MailClusterFailover=1
Disable mail router cluster failover (e.g. for diagnosing routing problems):
MailClusterFailover=0
Runtime activation via the server console:
set config MailClusterFailover=1

Notes & pitfalls

  • Only takes effect in an actual Domino cluster; without cluster membership the parameter has no effect at all.
  • Configuration in the server configuration document (Router/SMTP → Advanced → Controls → Cluster failover) is recommended; the notes.ini variant is equivalent but harder to keep consistent in a cluster.
  • Without replicated mail files, the router cannot deliver — a missing replica leads to messages remaining in mail.box or as dead mail.
  • Takes effect immediately after set config MailClusterFailover=…; restarting the Router task is not strictly necessary but speeds up adoption.
  • Should be set consistently on all cluster members and on Domino servers routing into the cluster, to avoid inconsistent behavior.

Sources (HCL Product Documentation)