How do you track your customers and communicate with them in a B2B company?

My co-founder and I are trying to learn more about how founders/PMs/growth/customer success managers at B2B companies track their customers and reach out to them via email, phone or in-app text.

We're seeing data in databases, Salesforce, CRMs, internal dashboards, Mixpanel. And then automatic communication seems to happen via Mailchimp, customer.io + a lot of ad-hoc that's not tracked. Was wondering if anyone had a system that works well for them.

Would love to have an open conversation about it here. And if you have 3 mins, please fill out this survey too: https://meettalkative.typeform.com/to/UP31zk