Nearly five months after the August 2008 exchange, Satoshi wrote to Adam Back one last time, the day after Bitcoin v0.1 was released. The load-bearing line of the email — Satoshi’s own announcement of the v0.1 release to one of the first cypherpunks he had contacted — reads:
I just released the open source implementation of my paper, Bitcoin v0.1. Details, download and screenshots are at
www.bitcoin.org
To give Back a high-level sense of how the project was being received, Satoshi forwarded part of Hal Finney’s response from the cryptography mailing-list thread. The Finney quote is independently published in the metzdowd.com cryptography mailing-list archive and lives in its canonical home at the Finney response entry (2008-11-07); the two lines Satoshi specifically forwarded so Adam could see what was being shown were:
Bitcoin seems to be a very promising idea. I like the idea of basing security on the assumption that the CPU power of honest participants outweighs that of the attacker.
This is the last known direct communication between Satoshi and Adam Back. Back did not engage with Bitcoin until 2013, and later founded Blockstream in 2014. The five-email chain — spanning 2008-08-20 to 2009-01-10 — documents Satoshi’s outreach to the creator of Hashcash, the referral that surfaced Wei Dai’s b-money, and Satoshi’s final notice that the working system had launched.