Deliverability reporting
CraftNudge is not a warmup tool and does not place mail in inboxes. What it does is show you the raw signals every other tool smooths over — so when something goes wrong, you can see what and why instead of guessing at a score.
| 250 | accepted | Queued by Google for delivery |
| 421 | deferred | Rate limited — you are sending too fast |
| 550 | rejected | Mailbox unavailable or blocked |
| 5.1.1 | Address does not exist Your list data is wrong. Verify, do not resend. |
| 5.7.1 | Blocked — reputation / policy The receiver distrusts your sending. Slow down. |
| 5.2.2 | Mailbox full Temporary, on their side. |
When Google accepts a message it says 250. When it is throttling you it says 421. When it rejects outright it says 5xx. Most tools throw that reply away. CraftNudge stores it against the send, so a wave of deferrals shows up as the earliest warning you will get that an inbox's reputation is slipping — before a single bounce.
A 5.1.1 means the address does not exist: your list data is wrong. A 5.7.1 means you were blocked for reputation or policy: your sending is the problem. Same bounce rate on a dashboard, opposite fix. CraftNudge reads the DSN code out of every bounce and tells you which disease you have.
Apple's Mail Privacy Protection pre-loads tracking images, which inflates open rates with opens by nobody. Anyone with images off shows as never opening, which deflates them. Open tracking is off by default here, and where it is on, we treat opens as directional rather than gospel. The number that is actually true is replies — and those we detect exactly.