> > Mails are superior in announcing to multiple people > > People who are known at time of sending. A slack message can be searched by those joining the team much (much) later, those who move teams, in-house search bots, etc.

People use slack search successfully? It's search has to be one of the worst search implementations I have come across. Unless you know the exact wording in the slack message, it is almost always easier to scroll back and find the relevant conversation just from memory. And that says something because the slack engineers in their infinite wisdom (incompetence) decided that messages don't get stored on the client, but get reloaded from the server (wt*!!), so scrolling back to a conversation that happened some days ago becomes an excercise of repeated scroll and wait. Slack is good for instant messaging type conversations (and even for those it quickly becomes annoying because their threads are so crappy), not much else. I wish we would use something else.