Store 'Last Activity' for Users

Managing end users can be complicated if you want to purge stale users on a rolling basis. The ticket history can be valuable particularly if the person only periodically reaches out. There is not a good way to do this on a time basis-- e.g. purge users not active in the last 12 mo. 'Last login' does not capture ticket exchanges, or involvement in side conversations. It would be ideal if the system could reflect an updated timestamp anytime someone sends an email, receives an email, is sent a side conversation email, sends a reply to a side conversation email, engages in a chat, interacts with the bot, or logs into the system.