I ran 10,000 outbound sequences across six domains last quarter and watched Apollo report a 4.2% "bounce rate" on a list that my SMTP logs told a completely different story about. When I dug into the raw delivery receipts, I found three separate failure modes all bucketed under that same number — and each one pointed to a different problem requiring a different fix. Most articles about outbound email bounce rate explained B2B stop at "hard bounce = bad address, soft bounce = temporary." That taxonomy is real, but it's also nearly useless if you're debugging an actual campaign. Here's what the tool vendors aren't surfacing. Your Bounce Number Is Three Different Problems Wearing One Label Let me give you the actual technical breakdown before touching what tools report. At the SMTP layer, rejection codes are structured: 5xx codes are permanent failures, 4xx codes are temporary deferrals. That's the foundation. But "bounce" in your sequencer dashboard almost never maps cleanly to this.…