03 / IN THE FIELD · 5 MIN READ

Work Through a Bounce, One Signal at a Time.

Collect evidence before changing records. A targeted check is more useful than repeatedly scanning every possible cause.

1. Read the Recipient’s Response

Capture the SMTP reply, enhanced status code if present, timestamp and affected recipient provider. Temporary 4xx and permanent 5xx classes call for different handling; the accompanying explanation matters. A quota, invalid address or policy rejection is not automatically a blacklist event.

Reference: RFC 5321 §4.2 — SMTP replies.

2. Map the Real Sending Path

Identify which service handed the message to the recipient. Keep web hosting, incoming MX, transactional email and bulk-mail platforms separate. If the rejection references an IP, compare it with trusted outbound logs rather than substituting the website’s A record.

3. Check Published DNS

Use Mail DNS to inspect the exact domain. Confirm the values against your provider’s setup instructions. Missing records, multiple policies and conflicting null MX deserve review—but this desk does not validate every mechanism or discover inherited policy.

4. Inspect Authentication on a Real Message

Use a known test recipient you control and the mail provider’s message trace or authentication results. DNS publication cannot prove that a sender used the expected envelope identity or signing domain. This site does not send test mail or upload headers.

5. Inspect the Sending IP

Run the IPv4 SpamCop check when relevant to the rejection. Compare PTR data with your provider’s expected hostname and SMTP greeting using its administration tools. This desk shows published PTR names but does not perform forward-confirmed reverse DNS or a greeting test.

6. Change Only What the Evidence Supports

Stop unauthorized sending, correct the actual record or account issue, and follow your provider’s process. Avoid replacing an entire SPF record with a generic example or changing production DMARC policy to make a warning disappear.

7. Retest and Escalate Clearly

After appropriate cache and retry intervals, repeat a small authorized test. If the problem remains, send the responsible provider a sanitized response code, time, sending IP, affected domain and the steps already checked. Do not publish full message bodies or credentials.

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