I maintain "API documentation" for my coworkers to refer to when they interface with me. In them I specifically call out that I do not view Slack as an instant

I maintain "API documentation" for my coworkers to refer to when they interface with me. In them I specifically call out that I do not view Slack as an instant response channel. I have a cell phone they can use if they need that type of SLA. Slack and Email are asynchronous. I have stuck with that since I started here and everyone seems to understand that those are the SLAs I commit to. So far no one is upset with me about it.