Read the signal.
Find the system.
One email passes through several independent systems. A sending dashboard, an SMTP reply, a DNS lookup and a mailbox observation each answer a different question. Start here to follow the evidence without mistaking one checkpoint for the whole journey.
Explore the six foundationsROUTE → RESPONSE
RESPONSE → NEXT TEST
Guides for interpreting delivery evidence. No invented inbox score. No customer data.
- Sending app
- Relay / MTA
- Recipient MX
- Gateway
- Mailbox
Each arrow is a separate handoff. Start by asking which system actually responded.
One route.
Several kinds of proof.
If a message is deferred, rejected or missing, first locate the last system that can prove it saw the message. Then preserve its exact reply, identity and time. These six guides form a reading path: follow the journey, identify its owner, interpret SMTP responses, and test authentication and DNS claims.
You can read every guide without registering. They explain what evidence can establish—and what remains unknown until a receiving system or mailbox is checked.
Begin with the delivery pathFundamentals
Start by identifying the route and the organization that owns each part of it.
Follow the entire delivery path
Map the route from sending application to recipient mailbox and locate the evidence at each handoff.
Read the articleFind the system that answered
Separate the access network, sending relay, receiver and security gateway before escalating.
Read the articleTroubleshooting
Interpret a reply before changing infrastructure, content or volume.
Identity & routing
Read authentication and DNS results without treating them as proof of inbox placement.
Seeing a real delivery change?
Capture the provider, route, time, redacted SMTP/NDR response and what changed before making a new move. Open the browser-local worksheet without joining a list; an email link is optional.
Bring a real response.
We'll trace the path.
If your team has a specific provider reply, a sudden change in placement or conflicting dashboard numbers, Sky can scope an evidence-led review. Your sending permissions and production changes remain yours.
Explore deliverability audit