It seems obvious to me that we shouldn't draw a special distinction between chats and emails. In practice most chat clients give you lots of email-like function

It seems obvious to me that we shouldn't draw a special distinction between chats and emails. In practice most chat clients give you lots of email-like functionality unless you go out of your way to configure them not to - timestamped history, search, archival of attached images, etc. While chat is "realtime" it's often used asynchronously just like email, and it's possible to send emails in near realtime if you have notifications turned on. I would personally hope that if someone is obligated to retain records, turning on an 'auto-delete' for any kind of record would be strongly discouraged, regardless of whether it's chats, emails, voicemails, etc. They could always just talk in person, then there's no recording to delete.