Backup your Redis data, then run:

redis-cli smembers BAYES_HAM_keys | while read -r PREFIX; do
  if [ -n "$PREFIX" ]; then
    redis-cli --scan --pattern "$PREFIX*" | xargs -r redis-cli unlink
  fi
done

When learning multiple messages with rspamc learn_spam or rspamc learn_ham, Rspamd may learn more messages than it actually needs. For example:

• You have 0 messages learned as spam
• You have 0 messages learned as ham
• You run rspamc learn_spam some_dir with a dir containing 1000 messages
• All of the 1000 messages will be learned, leading to ressource waste

Instead, if you learn some ham, then some spam, wait and repeat, then Rspamd won't need to learn all the messages, as some of them will already be classified as spam/ham with the already learned messages.