A possible solution for load balancing is to introduce a new map
type that makes random selection.
randmap:/file/name
The file contains a list of reponses, one response per line,
ignoring leading whistespace, trailing whitespace, and empty
lines. Each map query returns a randomly-selected response.
randmap:!one!two!three
Split the text after ":" on the first character, producing a
list of responses (one, two, three). Each map query returns a
randomly-selected response.
That should be enough to load-balance deliveries over mail delivery
transports.
The following example will deliver local mail locally and load-balance
non-local mail over smtp0: and smtp1:.
/etc/postfix/main.cf:
transport_maps = hash:/etc/postfix/transport, randmap:!smtp0:!smtp1:
/etc/postfix/transport:
example.com local:
mail.example.com local:
To implement different weight factors, repeat smtp0: and smtp1: a
different numbers of times.
Wietse
