Automated email and SMS sequences triggered by customer behaviour - welcome, abandoned cart, popup win-back, post-purchase - that run 24/7 without anyone hitting send. Flows are the money machines of email: campaigns are one-off efforts, flows compound every day. That is also why they deserve the testing discipline most brands reserve for their website - branch the flow, split the traffic, lock in the winner, test the next variable. The tell that your automations are underbuilt is a campaign-heavy revenue split: if manual sends are carrying the channel, you are doing daily labour that a flow should be doing in your sleep.
Benchmark. Flows should generate 50-70% of your email revenue. Build in priority order: welcome, abandoned cart and popup win-back first. If campaigns are carrying more than half the channel, the automations are underbuilt - fix that before sending more.