Every pipeline carries deals that are dead but not buried: the prospect won't say no, you won't stop hoping, and both calendars quietly pay for it. The breakup note exists because someone has to end it, and ending it turns out to be the most reliable way to find out it isn't over.

It works through relief. “If priorities shifted, tell me and I'll close the file” removes the thing that made replying expensive: the obligation to have good news. People who couldn't bring themselves to send a status update will answer permission to quit almost instantly.

Earn it first. Sent too soon, it reads as a tantrum; after a real sequence of useful touches it reads as professionalism. It's the last move, and being last is what gives it weight.

Write it warm and final, with one exit: you're closing the file, no hard feelings, and here's the single thing that would reopen it. No guilt, no “I've tried reaching you several times,” no invoice of your effort. The goodwill is the point; this market is smaller than it looks.

Honor whichever answer comes. Silence means close it truly and stop paying the mental rent. A “wait, don't” means one concrete next step booked inside the same conversation, because a revived deal that returns to drift only gets one resurrection.

“Wait, we're still interested!” The reply you wrote it hoping for. Calendar the next step in the same conversation, or you've spent the move for nothing.

“(Nothing)” Also an answer, and the useful kind. Close the record, keep the goodwill, recycle the attention into live deals.

“Now's bad, honestly. Try us next quarter.” A date from them, unprompted, is different from a stall from you. Book the reminder and hold them to their own words.