The true power of PowerMail only comes to light when employing multiple machines. To access multiple storage backends (which each run pptalker), these need to be defined in power.conf. To do so, define the 'backends' configuration field, which lists each backend and which 'group' it belongs to aswell as its priority.
Each backend is listed according to the following syntax: 'group:priority:ipaddress'. Below a list of sample configurations and what they mean:
Mail is stored over 192.168.0.1 and 192.168.0.2. If redundancy-target is set to 2, both backends will always receive a copy of each message. If this target isn't met, email reception is denied. Each server is in its own group, which tells PowerMail that the two hosts are mutually redundant.
If redundancy-target is set to 1, the default, email will be sent to the backend with the most free disk space available. Alternatively, if spread-load is specified, it will be sent to the host with the lowest load average.
Mail is stored on either 192.168.0.1 or 192.168.0.2, according to the spread-load or spread-disk specification above. If both of these are unavailable, mail is stored on 192.168.100.100.
With redundancy-target=2, mail is normally stored on 192.168.0.1 and 192.168.0.2. If 192.168.0.2 is down, it will be stored on 192.168.0.1 and 192.168.100.100.
When not operating over localhost (127.0.0.1) configuring a password is mandatory. The password must be identical over all nodes in your PowerMail constellation. It is configured in power.conf and pplistener.conf.
This is advised even when running on localhost!