What’s a secondary got to do
The last step is to tell the secondary where to find the recipient map. This is done using the relay_recipients_map facility in main.cf. Here’s what one looks like:
The relay_slacker file is the one that’s being synced with our perl script. The other file is very important as well, though! It’s a raw list containing wildcard entries for all the relay domains for which we’re not tracking a map of valid recipients. THIS IS CRITICAL! If you’ve defined any recipient maps at all, then postfix will expect all domains relayed to be covered by the recipient maps. You must include wildcard records in this other file for domains that you’re not syncing. Like this:
If you fail to do this, then postfix will reject all mail for the other relay domains.
Next, do a « postfix reload » and run some tests to make sure relaying is running ok.