Was at a startup that was super low-overhead (and as dysfunctional as a 4 person team could be), we used Zapier to automatically create Gmail drafts as replies

Was at a startup that was super low-overhead (and as dysfunctional as a 4 person team could be), we used Zapier to automatically create Gmail drafts as replies to new lead enquiries on the website and follow-up responses as needed. We could then spice up the response if needed, or just bulk run through and hit "Send". Appears personal to all email systems and spam filters, but actually was semi-automatic marketing automation.