Can I use DKIM verification without DKIM signing?
You can disable DKIM signing in amavisd config file, then restart amavisd service:
$enable_dkim_signing = 0;
Amavisd config file could be one of below:
- RHEL/CentOS/OpenSuSE: /etc/amavisd.conf
- Debian/Ubuntu: /etc/amavis/conf.d/50-user
- FreeBSD: /usr/local/etc/amavisd.conf
Also, iRedMail has its own support forum: http://www.iredmail.org/forum/ You can always get quick response in the forum.