This sequence goes to the mutual contact, never to the investor. Its job is to make a favour easy to grant and easy to refuse. Investors respond to introductions from people they trust; the person granting the introduction is spending some of that trust on you, so every message here respects that.
Who to put in it
One row per investor, addressed to the one person best placed to introduce you. If two contacts know the same investor, pick one; two requests for the same intro embarrass everyone. Run this as a small campaign with a handful of rows, and check every field by hand in the To check queue before the first send. A wrong investor_name or fund_name here is not a typo, it is a burnt bridge.
Do not use a shared sending mailbox for this. Send from your own address, the one the contact already knows, so the thread looks like what it is: a personal request. The rotation and mailbox choices described in mailbox rotation explained are for volume campaigns, not for this.
What to change before sending
Write one_liner as a single plain sentence that someone outside your industry could repeat. It appears inside the forwardable paragraph in step two, so it must work in the contact’s voice as well as yours. Test it by reading step two aloud as if you were the contact. If you have a deck, do not attach it; send it as a tracked offer link only after the investor has agreed to talk, following the golden rules of sending offers and proposals.
How to read the replies and when to stop
“Sent, they are open to it” means you now write to the investor yourself, referencing the contact by name, and take the contact out of the campaign. “Let me check with them first” is the double opt-in working as intended; wait, and do not send step two. “I do not know them well enough” is a no; thank them and mark the reply Not interested so step three does not send.
Silence after step three is an answer. Do not add a fourth step and do not raise it in person unless the contact does. If the round closes, send the update you promised, whether or not the introduction ever happened.