Why this is the cheapest pipeline you have
A lead who took three calls and then went quiet knows who you are, understands roughly what you do, and has already spent political capital internally considering it. Compare that to a cold prospect who knows nothing.
The reason people do not work these lists is that it feels like failure to go back. It is not. In most cases the deal died for a reason that has since expired.
Match the message to the reason
They ran out of budget. Come back near the start of their next budget cycle, not before.
Hi {first name}, you mentioned last {time} that budget was the blocker rather than the fit. New cycle now, so thought it was worth one message. If the timing works I would pick up where we left off, and if not I will leave it another year.
The champion left. Two moves: follow them, and approach the replacement.
Hi {first name}, congratulations on the move to {new company}. We spoke when you were at {old company} about {problem}, and I suspect it followed you. Happy to pick it back up if it is relevant here.
There was no decision maker in place. Watch for the hire.
Hi {first name}, saw {company} has a {role} in post now. We had started a conversation about {problem} before that seat was filled. Worth restarting?
They chose a competitor. Wait six to twelve months. That is when the gap between the demo and the reality shows.
Hi {first name}, you went with {competitor} last year, which was a reasonable call at the time. Not here to relitigate it. If the {specific limitation} has become annoying, I would be happy to talk. If it has not, glad it worked out.
They just went quiet. The most common, and the easiest.
Hi {first name}, we spoke about {specific thing} last {time} and then life happened, on my side as much as yours. {One thing that has changed} since. Worth fifteen minutes, or should I leave it?
What makes these work
Each one names the actual reason rather than pretending the silence did not happen. Each gives an explicit way out, which is what makes people comfortable enough to reply. And each asks for less than the original conversation did.
Building the list
Export closed-lost opportunities from your CRM going back eighteen months, filter to the ones that reached at least a second conversation, and check what has changed at each company: funding, new leadership, hiring, expansion. Those changes are your opener. It is the highest-yield list in your CRM and most teams never touch it.