Inboxes (*October 1, 2025*) I use X DMs, Signal, WhatsApp, and iMessage for most of my conversations. But I'll mark messages as read, start composing a reply in my head, get distracted, and then forget the whole thing existed. This isn't about bad intentions. I just always feel behind. Email is different. The inbox gives me a clear boundary. My daily routine is simple: delete spam, archive what doesn't need a reply, answer anything I can right now and archive it, or create a task and move on. Archiving is explicit, so nothing gets accidentally skipped. Gmail pulls archived emails out of the inbox but keeps them in "All Mail". I can always search for them later. The black and white approach works. Empty inbox means I'm done. Anything left means I have work to finish. Messaging apps lack the structural affordances that make email manageable. There's no equivalent to archiving, no definitive completion state. Conversations persist in an undifferentiated stream where recency determines visibility rather than importance. The endless list creates an open loop, a perpetual sense of incompleteness that email's Inbox Zero philosophy explicitly addresses through its bounded workflow. Merlin Mann's Inbox Zero wasn't originally about numerical emptiness but minimizing "the amount of time an employee's brain is in his inbox". The method provides psychological closure through explicit actions: delete, delegate, defer, respond, or do. Each email gets processed once using these categories, then exits the primary view. This "touch it once" principle prevents the paralysis of perpetual re-evaluation. Email clients support this workflow architecturally. Archiving removes items from the inbox while preserving searchability. The spatial metaphor of "inbox" versus "archive" creates a clear boundary between active and resolved states. Messaging platforms flatten this distinction entirely, treating all conversations as perpetually active regardless of actual status. The binary completion signal (empty versus not-empty) removes ambiguity about progress. This differs fundamentally from messaging apps where "caught up" remains subjectively defined and the interface provides no feedback confirming completion. The lack of closure mechanisms means conversations never truly resolve, they just scroll down into inaccessibility.