The old day’s holy grail of marketing, that is still functioning as a marketing channel for now with over 4b users worldwide.
Unlike websites, due to emails’ limitations, there were very few advancements to the kit. It has only basic tracking but at least we can feasibly put movie gif in it now due to internet improvements. Plus there are templates everywhere with Canva, Mailchimp, [insert CRMs].
The channel is now usually hooked to automations if not for day-to-day business use and is still a workable mid-late funnel for conversion in many playbooks.