Use central predefined 4096 bit DH params file (from Mozilla https://ssl-config.mozilla.org/ffdhe4096.txt ) instead of creation one via openssl command to speed up the installation. Thank you to @ahrasis for code suggestions.

Rename Mailman data directory if it exists and Mailman is not installed to prevent broken routes (#6314)

- Added optional enforcement of a max retention period via client template
- Added anonymize-ip option