Ordering is too expensive. Don't ever count on it when using an asynchronous queue. It's akin to storing session in a cache -- you're mixing your metaphors.

A queue should NEVER drop messages - otherwise it's a shit queue. Or you have a bug in your application code that needs to be fixed.

Poison messages are DEFINITELY A SMELL. This means you essentially have a broken interface contract. The code that is adding messages is expecting one thing -- code that is processing messages is expecting a different thing. It needs to be fixed by clearly documenting your message queue expectations and fixing your code. Most likely you need to add clear expectations for the lifetime of a message.