That works well when I remember the sender, but I don't always notice who sent it :(

In those cases I go back in the history of chats that I visited with either CMD+[ or the dedicated "clock" button

Wait, what clock button?

EDIT: Holy shit, thank you!

You're welcome! Notice that you can go also forward in the history with CMD+] and If you happen to have back and forward buttons on your mouse (like an MX master) they also work ;-)

I do that too, thanks! Alt+left/right arrow works too, as normally for the browser.