Evidence and decisions
Review the agreed routes, compare authentication and receiver responses, rank likely causes and recommend a testable remediation sequence. Record missing evidence as a limitation—not as a confirmed cause.
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01 / DIAGNOSE
Email deliverability consulting, grounded in evidence.
Understand why messages are delayed, rejected or landing in spam before changing the sending setup. Sky combines consulting with a technical audit of the agreed route: available SMTP responses, authentication, audience history and receiver evidence.
Book a discovery callSKY / DELIVERY PRACTICE01 / EVIDENCE MAP
What changed—and where?
ILLUSTRATIVE QUESTIONMicrosoft mail starts deferring after volume increases.Is it the route, the pace, or a change in recipient response?
COMPARE THREE SOURCES — NOT THREE SCORES
TRANSPORTSMTP replies
Which IP and time window show 4xx deferrals? Did retries recover?
IDENTITYSender & route
Did a domain, IP, authentication setting or traffic mix change?
RECEIVERSNDS / JMRP
Where authorized, compare IP signals and reported complaints.
IF DEFERRALS RISEHold volume on the affected route. Investigate the cause. Retest against a baseline.
01WHEN THIS HELPS
For teams facing a delivery change—or needing a second opinion before changing a provider, IP or sending domain.
02EVIDENCE & INPUTS
Read the evidence
across layers.
01
SMTP accept, reject and deferral codes
02
SPF, DKIM, DMARC, alignment and sending identity
03
Yahoo, Gmail and Microsoft signals where available
04
Complaints, bounces, suppressions and list provenance
05
Seed tests as a sample, not an inbox guarantee
03 CONSULTING + TECHNICAL AUDIT
A diagnosis first.
An agreed change next.
Consulting helps your team decide what to investigate and why. The technical audit examines the available evidence and turns it into a written issue map. Neither silently authorizes changes to a live sending system.
Production changes
DNS changes, integrations, live sending changes and ongoing monitoring require a separate agreed scope and your approval. We define who implements each change, who can pause it and how it will be checked.
Start with the right evidence, not unrestricted access.
Bring the affected route, time window, recent changes and a description of audience permission. Relevant redacted SMTP replies, message headers and reports can be reviewed through an agreed secure process. Provider dashboards require your authorization and may have incomplete or unavailable data. Do not put passwords, API keys, recipient lists or private logs in the enquiry form.
04 AUTHENTICATION + REPUTATION EVIDENCE
Check the identity.
Then read the response.
A published DNS record is not the same as a passing message check. We compare the sending identity with available message results, then look at the receiver and placement evidence. Authentication is necessary context—not proof of inbox placement.
- SPF Sender Policy Framework
- Check whether the sending IP is authorized for the envelope-sender domain. Compare the published policy with the result on the message being investigated.
- DKIM DomainKeys Identified Mail
- Check the signing domain and whether the message's signature verifies. A configured selector alone does not show that every sending route signs correctly.
- DMARC Domain-based Message Authentication, Reporting & Conformance
- Check whether passing SPF or DKIM aligns with the visible From domain. Review authorized reports where available, without assuming they describe inbox placement.
- Reputation & placement Interpret each source in context
- Compare available provider trends, complaints and representative test-inbox observations with the affected route and time window. A seed result is a sample, not every subscriber's experience.
Technical reference: Google sender guidelines and Yahoo sender requirements. Requirements and available signals depend on the receiving system.
TEST SKY-OWNED TEST INBOX INVENTORY
A controlled test.
Not every inbox.
When placement is part of the question, Sky uses its own test inbox inventory to observe selected receiving accounts. We compare those samples with route evidence rather than turning one test into a universal inbox score.
INVENTORY INCLUDES
- Gmail
- Microsoft Hotmail
- Yahoo Mail
- Microsoft 365
- Google Workspace
- US broadband / cable email accounts
The selected accounts and available coverage are agreed for the test. Consumer mail, business tenants and broadband/cable email accounts can have different receiving rules. An access network is not itself proof of a mailbox-placement result.
Choose the route and receiving accounts.
Agree the sender, representative message, selected mailbox coverage, test window and reporting format before the test.
Keep the result in context.
Compare observed placement with SMTP responses and authorized provider evidence. Test accounts do not reproduce every subscriber's history or tenant configuration.
Change one relevant variable.
Use the finding to support a scoped investigation or ramp decision. Repeat testing and follow-up are defined in the engagement; no fixed turnaround or inbox outcome is implied.
05THE WORKFLOW
What happens after
we start looking.
Reconstruct the path
Follow a message from sending system to receiver response. Separate a transport failure from a placement problem.
Rank the causes
Test the identity, infrastructure, audience and content hypotheses against the evidence.
Define the next test
Document the recommended change, its owner and the signals to compare. Implementation and follow-up tests are agreed separately.
06A CLEAR WORKING BOUNDARY
We know which part
belongs to whom.
What we need
An affected route and time window, recent changes, audience-permission context, and relevant redacted evidence through an agreed secure process. Access to provider signals must be authorized.
What we do
Trace the agreed sending path, compare available evidence, separate findings from hypotheses and document prioritized recommendations. This scope is diagnostic and advisory.
What you retain
Ownership of accounts and the audience relationship, approval of production changes and final sending decisions. Hands-on implementation and ongoing monitoring are separately agreed.
07WHAT YOU LEAVE WITH
A next step you can act on.
A written issue map, a prioritized remediation sequence and a measurement plan for the next sends.
See this engagement scope