Recently I signed up for a Calend.ly invite on a website, and after only giving them my email, they automatically found my LinkedIn and sent an automated connection request with a personalized email. Does anybody know how to do this? I'm sure they're using Zapier sequences. Still, I'm unsure of the first tool they're using to identify my LinkedIn with an email that's not even associated with my LinkedIn account.

They must be using a prospecting tool like crunchbase or lusha which would've indexed more than one emails of yours and probably the other one must be connected to your linkedin.

Thanks for the answer, we're doing more research as well and I can let you know if you're interested in our results

Yes, definitely!