SpamAssassin (spampd) ignoring user_prefs

I'm still not 100% clear on whether spampd is calling spamassassin or spamc, if it is calling spamc you need to set allow_user_rules to 1, if not, it should look for the user_prefs in the directory of the user calling spamassassin, and that directory only.

I don't think you will be able to use individual user_prefs from in spampd, they specifically mention that per-user whitelists are not available. They also mention that per-user preferences are a To-Do..

From the notes on switches

Turns on the SpamAssassin global whitelist feature. See the SA docs. Note that per-user whitelists are not available.

From the To-Do section on github

Per-user preferences: The jury is still out on this one. I'm thinking more and more that most per-user prefs should be specified on the final mailbox server. Why? Because SMTP isn't designed with per-user preferences in mind. On a relay server, the same message body can go to multiple recipients who may have wildly different preferences when it comes to handilng junk mail. The exception here might be the use of LMTP protocol, which bears further investigation.

I'm guessing they assume the users will have .procmail filters.

What are the permission settings on your user_prefs file? Verify that its readable by the spam assassin daemon. They should probably be 644.

Failing that, what user are you running SA as? According to this resource here, certain usergroups for the daemon result in it checking for config files in /home/spamassassin. Admittedly, this is Debian, so the Ubuntu behavior might be different.

You have to use -u ${recipient} argument for spamc in /etc/postfix/master.cf:

spamassassin unix -     n       n       -       -       pipe
    user=spamd argv=/usr/bin/spamc -u ${recipient} -f -e  
    /usr/sbin/sendmail -oi -f ${sender} ${recipient}