Delivering Outbound Messages Via Clustered Slaves
Starting v7.6, administrators can relay outbound messages through configured slaves in a clustered environment. This feature provides redundancy for outbound email delivery. Consider the following scenario as an example:
- A user sends an outbound email to firstname.lastname@example.org. This message is initially sent to the MASTER Xeams.
- If the first delivery attempt fails, message is sent to one of the configured slaves. Communication between MASTER and SLAVE is done via HTTP(S) rather than SMTP.
- This option is turned on by default
- To turn it off, go to Server Configuration, SMTP Configuration, select the Advanced tab and uncheck Relay Thru Clustered Slaves
Confirming Message Delivery Through Slaves
Following methods confirm if a message went out through a slave.
- The color for Status Icon for email delivery will turn Blue
- The host name will start with "slave:" in
Emails That Are NOT Routed Through Slaves
- Inbound or Internet emails
- Original recipient belongs to a distribution list
- Smart host is used or the domain exists in hosts.txt file