There was recently a user in #zabbix that had issues where unreachable devices were never retried. It took a long time to realize that the user had set UnreachablePollers=0 in their proxy config file. Since the vast majority of users should never ever set UnreachablePollers=0, would it make sense to at least provide some kind of warning in the proxy/server log file if they've done that? Perhaps even put a comment above that option in the config to indicate not to set it to zero unless they know what they're doing (the user with the issue suggested this).