diff --git a/inventory/service/group_vars/mailman3.yaml b/inventory/service/group_vars/mailman3.yaml
index 4cb3f83873..73e9e89227 100644
--- a/inventory/service/group_vars/mailman3.yaml
+++ b/inventory/service/group_vars/mailman3.yaml
@@ -22,6 +22,8 @@ borg_backup_excludes_extra:
   - /var/backups/mailman-mariadb
   # Can regenerate indexes from source email files
   - /var/lib/mailman/web-data/fulltext_index
+  # Django will rebuild its caches as requests are made
+  - /var/lib/mailman/web-data/diskcache/
 # Exim Configs
 exim_queue_interval: '1m'
 exim_queue_run_max: '50'