The double opt-in intro
Ask both people before you connect them. One extra message removes the version where somebody has to decline in front of a stranger.
By Jerry Feng, Growth at Happenstance. Updated August 28, 2026.
The short version
A double opt-in intro is an introduction where the introducer checks with both people privately before connecting them, so nobody is put on the spot in front of a stranger. The requester supplies a forwardable paragraph, the introducer asks the other side, and the introduction goes out only after a written yes.
Why investors expect it
The practice has a named origin. In November 2009 Fred Wilson of Union Square Ventures wrote a post called The Double Opt-In Introduction, describing the volume that made him adopt it: “I send emails like that a lot. I might send a half a dozen or more every day”, and of the ones arriving, “I get even more emails like that. Sometimes dozens a day.” His rule was to ask each side to opt in before making the connection. Venture picked it up and it's now the default at most firms.
It stuck because the alternative pushes the cost onto the busier person. Connect two people cold and they can take a meeting they did not want, decline in front of the founder, or say nothing and look rude. Asking privately first removes all three, and the founder finds out quickly either way.
The second effect matters more over time. People open what a careful introducer sends, because everything that arrives from them has been checked first. That is why the etiquette holds even for people who get two intro requests a month rather than dozens a day.
Doing this with Happenstance
Whether you are the right introducer is a question about your own network, and it is answerable. Happenstance searches the accounts you connect, Gmail, Outlook, Google Calendar, Google Contacts, LinkedIn, Twitter and Instagram, so asking “Who else in my network knows Maya Osei?” returns the people who can reach her and the evidence behind each path, including whether it came from years of email or a single connection request.
It works the same way when a request lands in your inbox and you do not recognize the name. One search tells you how you know them, which is the difference between introducing a colleague and introducing a stranger. Friends and groups pool networks, so the answer covers your team as well as you. Happenstance is free. The free plan is the whole product, with usage limits on chat and web searches beyond your network. Pro raises the limits: unlimited web searches and results, higher chat limits, and CSV export.
The mechanics of paths are covered in warm introductions, and the best warm introduction software compares what else is out there. Founders on the requesting side of all this can start at Happenstance for fundraising.
Three short templates
Three messages make up the whole sequence, in the order they are sent. Keep each one under a screen and replace everything in brackets.
Template 1: replying to the person who asked
Subject: Re: intro to [Maya]
Template 2: checking with the person being introduced to
Subject: Intro to [Ravi Shah]?
Template 3: the introduction itself
Subject: [Ravi] <> [Maya]
The requester's side of this, including the paragraph they're supposed to hand you, is on how to ask for a warm introduction. For the wording of the connecting email in other situations, see how to make a warm introduction by email, and for the fundraising version of the whole loop, how to get warm intros to angel investors.
What Happenstance can see
Email is read as headers only. Message content and attachments never reach our servers. Yes. Your connections are searchable only by you, the friends you accept, and the groups you join, and sharing is always mutual. Your public profile shows a constellation of named people you know by default, which you can turn off anytime. We never share, sell, or use your data to train AI models. Happenstance is SOC 2 certified and DTI Trust Level 2; the full list of what is stored and for how long is on the security page.
Frequently asked questions
What does double opt-in intro mean?
It means both people agreed to the introduction before it was made. The introducer asks each side separately, usually forwarding a short paragraph about the person who wants the meeting, and only sends the connecting email once both have said yes. The alternative, connecting two people cold in a single email, forces one of them to decline in public.
Why do investors insist on double opt-in introductions?
Because they receive many more introduction requests than they can take, and a single-opt-in intro leaves them declining in a thread where the founder can see it. Checking first lets them say no privately, which costs the founder nothing and keeps the introducer usable. Fred Wilson of Union Square Ventures named the practice in 2009 and it spread through venture from there.
Who do you check with first?
The person being introduced to, meaning the busier or more in-demand side. They're the one whose time is being requested, and their answer determines whether there's anything to arrange. Ask them with a short forwardable paragraph attached and an explicit line saying a no is fine.
Does a double opt-in slow the introduction down?
It adds one message to each side, and it removes the awkward version where two people are stuck in a thread neither wanted. In practice the ones that would have converted still convert, and the ones that were never going to happen end instead of sitting unanswered for two weeks.
What do you say in a double opt-in check?
Four lines: who's asking, one sentence on what they do, what they want out of a conversation, and your own read on whether it is worth their time. Paste the requester's own paragraph rather than writing your own summary, and add one line of your honest read on them. That last line is the part that carries weight.
What if one side says no, or doesn't reply?
Tell the other person plainly and without dressing it up: not right now, and here is anything useful they said. Silence counts as a no after a week. Don't go back a second time on someone else's behalf, because that spends your relationship rather than theirs.
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