Try enabling that fedmsg plugin again.

roles/mailman/tasks/main.yml

@@ -74,19 +74,19 @@
   tags:
   - packages
 
-#- name: setup the mailman3-fedmsg repo
-#  copy: src=mailman3-fedmsg-plugin.RedHat.repo
-#        dest=/etc/yum.repos.d/mailman3-fedmsg-plugin.repo
-#  when: ansible_distribution == 'RedHat'
-#
-#- name: add the GPG key for the mailman3-fedmsg-plugin repo
-#  rpm_key: state=present key=https://copr-be.cloud.fedoraproject.org/results/ralph/fedmsg-python34/pubkey.gpg
-#  when: ansible_distribution == 'RedHat'
-#
-#- name: install the mailman3 fedmsg plugin rpm
-#  yum: pkg=mailman3-fedmsg-plugin state=latest
-#  notify: restart mailman3
-#  when: ansible_distribution == 'RedHat'
+- name: setup the mailman3-fedmsg repo
+  copy: src=mailman3-fedmsg-plugin.RedHat.repo
+        dest=/etc/yum.repos.d/mailman3-fedmsg-plugin.repo
+  when: ansible_distribution == 'RedHat'
+
+- name: add the GPG key for the mailman3-fedmsg-plugin repo
+  rpm_key: state=present key=https://copr-be.cloud.fedoraproject.org/results/ralph/fedmsg-python34/pubkey.gpg
+  when: ansible_distribution == 'RedHat'
+
+- name: install the mailman3 fedmsg plugin rpm
+  yum: pkg=mailman3-fedmsg-plugin state=latest
+  notify: restart mailman3
+  when: ansible_distribution == 'RedHat'
 
 - name: install packages when not using source extracts
   when: ansible_hostname != "lists-dev.cloud.fedoraproject.org"

roles/mailman/templates/mailman.cfg.j2

@@ -32,9 +32,9 @@ class: mailman_hyperkitty.Archiver
 enable: yes
 configuration: {{ mailman_webui_confdir }}/mailman-hyperkitty.cfg
 
-#[archiver.fedmsg]
-#class: mailman3_fedmsg_plugin.Archiver
-#enable: yes
+[archiver.fedmsg]
+class: mailman3_fedmsg_plugin.Archiver
+enable: yes
 
 [archiver.prototype]
 enable: yes