Warm Intros, Computed: Finding Trust Paths in Your Inbox
Short answer: A warm intro is a stranger you have never emailed, but who people you trust already know well. Trust-graph math finds these paths automatically by extending your relationship graph through your trusted contacts. So a cold sender with two real vouchers from your circle is surfaced, while a true stranger with no path stays in the cold pile.
The most valuable email is from someone you do not know yet
Direct contacts are easy. You already email them. The hard and valuable case is the stranger who matters: a founder two of your portfolio CEOs both know, a candidate your closest colleague worked with, a partner introduced through a trusted mutual. These are warm intros, and they are the lifeblood of how business actually moves.
The problem is they look identical to cold spam in your inbox. Both are from someone you have not emailed. A simple "do I know this address?" filter would bury the warm intro along with the noise.
How a trust path is computed
Personalized PageRank does not stop at your direct contacts. Trust flows outward through them. If you trust Sarah and James, and both Sarah and James genuinely correspond with a stranger, some of your trust reaches that stranger through them. The stranger gets a score that reflects how well-vouched they are, even with zero direct history.
The strength of the path matters:
- One weak voucher barely moves the score. A single thin connection is not enough.
- Two or more independent vouchers from people you actually trust lift a stranger toward warm. Independent matters: two vouchers that both route through the same single contact count as one real path, not two.
This is the network effect of a trust graph: the more of your real circle a stranger connects to, the warmer they get.
Why fakes cannot abuse it
The obvious worry: can someone manufacture vouchers? The defense is that a voucher has to be a genuine relationship from a contact's own mailbox, not just any edge someone claims. And a cluster of fake accounts hanging off one bought connection is a bottleneck the math down-weights: trust that reaches you only through a single cut point gets decayed. Earning two independent, real relationships inside your trusted circle is exactly the costly, human thing warm intros are supposed to represent.
It runs on your own mail
You do not fill out a social graph or import contacts. The intro paths are inferred from the metadata already in your mailbox: who you correspond with, and who they correspond with. When the cross-user signal is used, identities are hashed so no one sees plaintext addresses. See personalized vs public reputation for the privacy model.
FAQ
How is a warm intro different from a direct contact? A direct contact is someone you email. A warm intro is someone you do not email, reached through people you do. Both can land in your inbox; a true cold stranger does not.
Does this need other people to use the product? Direct scoring works on day one from your own mail. Warm-intro detection gets richer as more of a connected group participates.