The exchange's popularity in Iran was known inside [Binance]. Senior employees knew of, and joked about, the exchange's growing ranks of Iranian users, according to 10 messages they sent to one another in 2019 and 2020 that are reported here for the first time. "IRAN BOYS," one of them wrote in response to data showing the popularity of Binance on Instagram in Iran.

By August 2019, Binance deemed Iran – along with Cuba, Syria, North Korea and Crimea – a "HARD 5 SANCTIONED" jurisdiction, where the exchange would not do business, according to an internal document seen by Reuters. The May 2020 document included Iran on a list of countries headed "strictly no," citing Chief Compliance Officer Samuel Lim.

Even as Binance's stance on Iran hardened, its profile among the country's legions of crypto users was growing, traders said, citing their knowledge of the local industry.

Mehdi Qaderi, a business development worker, said he used a VPN to trade around $4,000 worth of crypto on Binance in the year to August 2021. "All of the Iranians were using it," Qaderi said of Binance.

Binance itself had supported the use of VPNs.

Zhao, Binance's CEO, tweeted in June 2019 that VPNs were "a necessity, not optional."