Sieve seems not powerful enough. I had this though experiment a few days ago: What if you could run code in a sandbox on the server (javascript, webassembly?) w

Sieve seems not powerful enough. I had this though experiment a few days ago: What if you could run code in a sandbox on the server (javascript, webassembly?) with api's (provided by the server) to access mailboxes/messages and to take actions (move to folder, change message flags), and perhaps some networking (e.g. dns blocklist)?