Amavisd + SpamAssassin not working, no mail header (X-Spam-*) inserted.

Amavisd has below setting in its config file /etc/amavisd/amavisd.conf by default:

$sa_tag_level_deflt  = 2.0;

That means Amavisd will insert X-Spam-Flag and other X-Spam-* headers when email score >= 2.0. If you want to let Amavisd always insert these headers, you can set it to a low score, for example:

$sa_tag_level_deflt  = -999;

Amavisd's main config file is different on different Linux/BSD distributions:

• Red Hat, CentOS, OpenBSD: /etc/amavisd/amavisd.conf
• Debian, Ubuntu: /etc/amavis/conf.d/50-user (and other config files under /etc/amavs/conf.d/)
• FreeBSD: /usr/local/etc/amavisd/amavisd.conf