This the first of two new tables introduced with postfix-2.12-20140618.
Wietse
The "random" lookup table performs random selection. This may be
used to implement load balancing, for example:
/etc/postfix/transport:
# Deliver my own domain as usual.
example.com :
.example.com :
/etc/postfix/main.cf:
transport_maps =
# Deliver my own domain as usual.
hash:/etc/postfix/transport
# Deliver other domains via randomly-selected relayhosts
random:!smtp:smtp0.example.com!smtp:smtp1.example.com
A variant of this can randomly select SMTP clients with different
smtp_bind_address settings.
The ASCII character after "random:" will be used as the separator
between the results that follow (do not use space, ",", ":" or
non-ASCII).
Some future version may support the form random:/path/to/file,
to load the list of random values, one per line, from a textfile.
To implement different weights, specify lookup results multiple
times. For example, to choose smtp:smtp1.example.com twice as often
as smtp:smtp0.example.com, specify smtp:smtp1.example.com twice.
