BRPOPLPUSH mentioned in the BLPOP doc.

commands/blpop.md

@@ -103,6 +103,12 @@ redis> BLPOP list1 list2 0
 2) "a"
 ```
 
+## Reliable queues
+
+When `BLPOP` returns an element to the client, it also removes the element from the list. This means that the element only exists in the context of the client: if the client crashes while processing the returned element, it is lost forever.
+
+This can be a problem with some application where we want a more reliable messaging system. When this is the case, please check the `BRPOPLPUSH` command, that is a variant of `BLPOP` that adds the returned element to a traget list before returing it to the client.
+
 ## Pattern: Event notification
 
 Using blocking list operations it is possible to mount different blocking