You cannot use milter-manager with Ruby 2.4.3. It's known issue. It has been fixed in Ruby 2.5.0 and https://github.com/ruby/ruby/tree/ruby_2_4 If you want to cherry-pick the patch see https://github.com/ruby/ruby/commit/3d4a397354fd8d27c5eb91ca5c3bd7afe9b11af0#diff-7875e170ada1a2b62a8c8798729afa11
milter manager: milter manager 2.0.9 Released
milter manager: milter manager 2.0.8 Released
milter manager: milter manager 2.0.7 Released
milter manager: milter manager 2.0.6 Released
milter manager: milter manager 2.0.5 Released
Thank you for reporting issue. I've executed createrepo command again with --checksum...
milter manager: milter manager 2.0.4 Released