I run a small bootstrapped open source startup in a niche space. Growth is slow but steady and we're starting to win larger customers as the product matures.

Recently, the leading vendor in this space ($50 million in funding, dozens of employees) has starting camping out in our community Slack and cold-emailing our community members, offering them thousands of dollars worth of free credits to switch to them. Emails are not exposed in our slack, so they are getting people's names and googling where they work to deduce their email.

The vendor's employees are registering under fake names so there's no straightforward way to ban them from the Slack.

Has anyone else been in this situation, if so what did you do?

I think you need to make people sign up, agree to TOS that prohibits solicitation, document the bad behavior, take it to a lawyer and sue for damages.

You gotta trap them somehow and prove damages.

I’m not a lawyer though so just a guess.

Remove them! Plus post about them openly on social media.. it'll give more traction to your product, plus expose such behaviors by big companies.

Ban them? You haven't said but I assume the vendor's presence in the Slack is not disguised. Either way, it's your Slack and you're entitled to determine who is welcome and who isn't. You are under no obligation to be providing your competitors with a free channel and free leads.

There isn't really much you can do about that. They'll find your customers one way or another (ie: GitHub stars, your packages, issues, etc.)

Don't worry about it and just focus on serving the customers you have.