As @corasaurus-hex says. I think it's all about the recipient and having a way for the recipient to escalate if they don't feel comfortable with the DM. As a counter example, I'd be super stoked if @cfleming unsolicitedly DM’ed me with a job offer. On the flip side though, an escalation shouldn't automatically lead to an account termination. I could see myself DM’ing, say @cfleming, a job offer in very good faith, but him being super annoyed by it and escalating. I'd be fine with having my attitude readjusted a bit, but would be very unhappy about having my account terminated for just one unknowing transgression. BTW, I'm using @cfleming here because we know each other's a bit. One could argue that a lacking feature in Slack is that there is no mute for dms.

another slack I'm a part of has enforcement guidelines https://github.com/CTFCircle/CoC#enforcement-guidelines