Ask HN: Potential problems integrating your business with services like Slack?

Here's the scenario: Say my website has a contact email. I can't afford a $5/mo email and possibly a mailing server/service. I don't have a viable business, this is just for testing. So one other option (since default mailing scripts in PHP on a rented server will probably never send out/be reached) is to use a form that is stored in a database. Well this now depends on if you open that database or not... some front end web app you log into say. But with something like a Slack Webhook I can get around my technical lacking with regarding to mailing and android dev. I now have the ability to receive a 'push notification' through slack through an android app by sending a curl request to that slack channel for support. Now the problem is, Slack "technically owns" this data right? I mean they're hosting it. I didn't read their terms of service. I'm not targetting slack either. I also wonder when I use free email from Google or Hangouts, etc... Hence you know I think you should host your own stuff when dealing with your client's businesses despite the ease that a Slack webhook might provide. I don't know it sucks haha, it would be so easy (and FREE) to just use that (slack webhook notification for email received from website users)