shit, my company had a "when a user is created or deleted in AD, do X" type of functionality, we could save so much freaking money money its ridiculous. Im still. planning on sitting down and building it.

They have that. Check out Quest/Dell/whatever ActiveRoles and other Identity Management type competitors. I think any big enterprise vendor has an offering. The problem with a lot of them is the price-they're pretty spicy. But they are going after enterprise players with deep pockets.

Cool, I'll take a look. I've evaluated a couple identity management solutions, but for the most part we don't need it. We have an AD/ADFS/SAML/etc... setup that works great for the most part.

I just want to avoid paying the stupid premium on stuff like the enterprise version of Slack just for AD integration.

Mattermost?

You're basically still writing the automation yourself at that point since it would just be a bot right? I'd think you might as well just create it as a separate service and have a bot interact with it or handle events from it in Mattermost/Slack/IRC/etc.

That's a pretty cool idea for Mattermost to have triggers that go off on new account creation.

Maybe a customizable welcome email as well for new team members.