A not-found result means a successful mailbox check did not find a matching copy at that observation time. It does not establish Spam placement, SMTP rejection, or permanent loss. First verify submission, destination, transport, matching, and observation conditions. If the mailbox could not be read, describe unavailable evidence instead; if the check is unfinished, keep it pending.
Confirm the destination and submission
Copy the test destination exactly from the current run. Compare it with the address used by the sending system, including any token or plus-addressed component. Check for an old panel list, a truncated local part, or a test sent to a personal address instead. A valid message sent elsewhere cannot be found in the intended mailbox.
Next, establish whether the message left the application. Save the queue or provider identifier and inspect relevant events. An application log saying created or queued may precede an ESP submission. A local preview does not demonstrate transport. Separate these stages before assuming the receiver silently removed a message.
Inspect transport events without inventing a folder
A temporary SMTP response can leave the message queued for retry. A permanent failure can produce a rejection or bounce under the sender's documented event model. Capture the exact code, response text, recipient, and time. Generic dashboard labels such as sent or delivered need the provider's definitions before they can establish a remote handoff.
Even a remote acceptance is not a user-visible folder observation. An intermediate gateway may have accepted the message before further processing. When transport acceptance and not-found evidence coexist, retain both facts. That combination is a useful support case; it is not permission to replace the missing result with an imagined Spam folder.
Check observation and matching
Confirm that the mailbox search completed successfully and that the relevant folders were observable. Access failures, timeouts, or unavailable credentials create an evidence gap. They do not show that the message was absent. Read the report's distinction between missing, unavailable, failed operation, and pending work.
Review the matching criteria with the available product diagnostics. Recipient tokens, message identifiers, and timing can matter. A forwarded or reconstructed copy might not preserve the identifier expected by the run. Do not repeatedly resend arbitrary copies until something appears without recording which send was matched; doing so can obscure the original failure and create duplicate observations.
Retest with a controlled correction
Correct an established address, submission, or route problem and generate a fresh test. Preserve the old run as a baseline. Use a distinct recorded identifier so the new copy cannot be mistaken for a late arrival from the earlier send. Compare observations at a similar stage and inspect the transport timeline for both.
If no cause is established, escalate with the destination, UTC timestamps, sender account or stream, provider event identifiers, exact responses, and observation state. Share only the data needed for support and redact secrets or one-time links. A clear unresolved case is preferable to a false diagnosis that sends the team toward unrelated content or DNS changes.
Frequently asked questions
Does not found mean the receiver deleted the email?
It does not establish that cause. Submission, routing, deferral, filtering, matching, and observation gaps need separate examination before choosing an explanation.
How long should I wait?
Use the sending service's documented retry behaviour and the test's observation contract. Record the time rather than assuming every route shares a universal delivery deadline.
Does a missing copy enter LDM's Inbox denominator?
The ordinary denominator is observed external received copies. Retain missing outcomes as separate coverage evidence instead of counting them as an observed folder.
Sources and scope
Source check: November 5, 2026. Source checking is separate from publication. Observations apply to the tested copies and conditions.