On https://docs.iredmail.org/install.iredmail.on.rhel.html there the note:
"Since official RHEL/CentOS and EPEL repositories don't have all required packages with the needed features, iRedMail team has built these packages and made them available trough the iRedMail repository enabled by default at installation time. You can view all available packages here, please check README and ChangeLog files under each directory for more details. Source RPMs (srpm) used by iRedMail team to build the binary packages are available here."
This is wrong for iRedMail 0.9.7
I disabled epel repo and a some components were not installed (amavis, awstats,...)