The argument is a bit ridiculous - simple logging of all messages sent also requires the same storage, and that is commonly done whenever each individual message and it&#x27;s delivery is considered important.<p>As long as the storage requirements are bounded by number of messages times number of recipients times some reasonable constant, it <i>is</i> perfectly feasible to assume that you will have sufficient storage; the storage requirements are finite and predictable, and it&#x27;s only a matter of your choice and priorities.<p>Acknowledging that doing X will require Y petabytes of storage and cost Z dollars may mean that you won&#x27;t do it, but it&#x27;s very, very different from stating that it&#x27;s impossible.