Reconstruct the path
Follow a message from sending system to receiver response. Separate a transport failure from a placement problem.
← ALL CAPABILITIES
01 / DIAGNOSE
Find the failure point. Then fix the right thing.
When delivery changes, it is tempting to swap IPs, rewrite subject lines or buy another tool. We start with evidence: transport logs, authentication, receiver behavior, complaints and representative placement tests.
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 senders seeing deferrals, blocks, spam placement or a sudden change in performance.
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
03THE WORKFLOW
What happens after
we start looking.
Rank the causes
Test the identity, infrastructure, audience and content hypotheses against the evidence.
Retest with a baseline
Change what matters first, then compare receiver and subscriber signals to the original state.
04A CLEAR WORKING BOUNDARY
We know which part
belongs to whom.
What we need
Recent provider-specific examples, sending identities, SMTP service events or server logs, and a description of how the audience was acquired.
What we do
Trace the sending path, compare receiver and placement evidence, isolate likely causes and document a testable sequence of changes.
What you retain
Account access and approval of any production change; the audience relationship and final sending decisions.
05WHAT 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