I understand if you are manager/owner you might be running comms via email. But internally all of that went to slack for good reason - lack of history is a feature, not a bug.
I am neither manager nor owner. Just another 1x engineer. 75% of my comms run over email. 25% over Jabber.
Not every software company uses Slack!
Email is good for having common interface. In my case it's ~abused in 99% of cases.
Also - you do not mention how much non-comms emails do you receive. While chat apps are fucky in terms of lock-in, lack of interop and tons of other things, lack of spam is nice.