&gt;trying to delete old messages is complex and sometimes impossible<p>I&#x27;m not familiar with ZeroMQ&#x27;s data structures, so forgive my ignorance. At the high water mark, why can&#x27;t the consumer throw away old messages instead of the producer throwing away new messages? There are no locks or bugs — that&#x27;s what the consumer does anyway.<p>I&#x27;m not saying that should be the default behavior, but perhaps an option. It&#x27;s cleaner than silently dropping new messages, then sending an entire buffer of old messages if the subscriber recovers.