On July 21, 2009, Satoshi had mentioned that he needed a “break” after 18 months of continuous Bitcoin development and asked Malmi for ideas about bootstrap applications that could help Bitcoin grow.
The following day, Malmi responded with a proposal that would prove historically significant: he suggested establishing a Bitcoin exchange service for euros. His proposal detailed pricing formulas and profit mechanisms to establish initial currency liquidity for Bitcoin.
On August 24, 2009, Satoshi provided detailed feedback on the exchange proposal, emphasizing that pricing should be backed by production cost rather than pure auction mechanics, and suggested minimum transaction sizes to encourage more user participation in trading.
Malmi went on to create and operate Bitcoinexchange.com, one of the earliest Bitcoin exchanges. The newly published emails revealed that Satoshi had been a key advisor throughout the exchange’s development, not merely a passive observer.
This collaboration directly led to what is considered the first known Bitcoin-to-USD transaction: on October 12, 2009, Malmi sold 5,050 BTC for $5.02 via PayPal through his exchange service, valuing each bitcoin at approximately $0.001 - establishing one of the earliest recorded price points for Bitcoin.
Source: Published by Martti Malmi on GitHub in February 2024 as part of his testimony in the COPA v. Wright trial. The full correspondence archive is available at mmalmi.github.io/satoshi/.