The Fastmail help documentation doesn’t provide a comprehensive list of header values. Maybe you can submit a ticket and ask Fastmail support for a list? Here are the ones I’ve found by trolling through message headers:AccountsAlertsCommercialCommunityPurchasesSpamA sample rule could look like:If *any* of the following conditions apply *A header called* x-me-vscategory *contains* commercial *Move to* (or *Apply label* or whatever) …

#!/usr/bin/env python3 import configparser import os import sys from selenium import webdriver from selenium.webdriver.chrome.options import Options from selenium.webdriver.common.keys import Keys from selenium.common.exceptions import TimeoutException from selenium.webdriver.support.ui import WebDriverWait from selenium.webdriver.support import expected_conditions as EC from selenium.webdriver.common.by import By config = configparser.ConfigParser() config.read("config.ini") chrome_options = Options() chrome_options.add_argument("--headless") driver = webdriver.Chrome(executable_path=os.path.abspath("/usr/local/bin/chromedriver"), chrome_options=chrome_options) driver.get("https://fastmail.fm") timeout = 120 try: element_present = EC.presence_of_element_located((By.NAME, 'username')) WebDriverWait(driver, timeout).until(element_present) # Send login information user = driver.find_element_by_name("username") passwd = driver.find_element_by_name("password") user.send_keys(config["default"]["user"]) passwd.send_keys(config["default"]["pass"]) driver.find_element_by_class_name("v-Button").click() print("Logged in") # wait for login to complete element_present = EC.presence_of_element_located((By.CLASS_NAME, 'v-MainNavToolbar')) WebDriverWait(driver, timeout).until(element_present) # click settings menu to make elements visible driver.find_element_by_class_name("v-MainNavToolbar").click() # And follow to settings page driver.find_element_by_link_text("Settings").click() # Wait for settings page to render, oh Javascript element_present = EC.presence_of_element_located((By.LINK_TEXT, 'Rules')) WebDriverWait(driver, timeout).until(element_present) # Click on Rules link driver.find_element_by_link_text("Rules").click() # Click on edit custom sieve code element_present = EC.presence_of_element_located((By.LINK_TEXT, 'Edit custom sieve code')) WebDriverWait(driver, timeout).until(element_present) driver.find_element_by_link_text("Edit custom sieve code").click() print("Editing") # This is super unstable, I hate that we have to go by webid element_present = EC.presence_of_element_located((By.CLASS_NAME, 'v-EditSieve-rules')) WebDriverWait(driver, timeout).until(element_present) print("Find form") elements = driver.find_elements_by_css_selector("textarea.v-Text-input") element = elements[-1] # Find the submit button elements = driver.find_elements_by_css_selector("button") for e in elements: if "Save" in e.text: submit = e print("Found form") # And replace the contents element.clear() with open("rules.txt") as f: element.send_keys(f.read()) # This is the Save button print("Submitted!") submit.click() except TimeoutException as e: print(e) print("Timed out waiting for page to load") sys.exit(0) print("Done!")