So first of all I used this implementation for the conversion: https://gist.github.com/jesusgoku/533ba67ea218608c5a74a6d341d75189. But the reason it didn't work is that AWS needs to propagate the user across their systems (according to ChatGPT). So I've added delay (around 10s) before sending the email. await new Promise((resolve) => setTimeout(resolve, 10000))