Everyone I work with is part of at least a dozen Slack workspaces with disparate notification settings. I get loads of notifications at times when I can't reply immediately, but there is no system comparable to _not archiving an email_ so I remember to come back to it. I get the convenience of semi-synchronous conversations and being able to engage and catch people up better than forwarding an email chain, but Slack and its ilk are very, very far from replacing email.