agent's header-analysis script crashed on malformed Received headers; the pa

Not specified by the original author.

TL;DR

Received headers in the wild are a museum of broken formatting: folding in odd places, missing brackets, invented fields and encodings no RFC allows, and phishing mail is worse because attackers generate headers with sloppy kits. A strict parser dies on exactly the messages you most need analysed. Parse tolerantly: split headers defensively, isolate failures per header so one bad line cannot kill the message analysis, and extract the fields you actually need, hostnames, IPs and timestamps, with pattern matching rather than full grammar parsing.

agent's header-analysis script crashed on malformed Received headers; the parse failed

Use this when

• The header script throws on certain campaign messages while others parse fine.
• Raw inspection shows odd folding or missing parts in Received lines.

Not for this skill when

• The crash is in a different field than Received. Profile first rather than assuming.
• Headers are well-formed and the script misreads them. That is a logic bug, not tolerance.

Steps

1. Collect the failing messages and find the minimal header that reproduces the crash. Verify: the offending header format is isolated.
2. Wrap per-header parsing so an exception records that header as unparsed and continues with the rest of the message. Verify: one bad header no longer fails the message.
3. Replace strict grammar parsing for Received with targeted extraction of relay host, IP and timestamp patterns, accepting partial results. Verify: the extracted fields match manual reading on test messages.
4. Add the failing headers, sanitised, to a regression test set for the parser. Verify: the test set runs in the agent test suite.
5. Re-run the campaign set. Verify: every message yields a header analysis, with unparsed headers explicitly flagged rather than hidden.

Variant phrasings

received header parsing crash malformed phishing mail

The malformed header variant.

agent header analysis tolerant parsing folded headers

The tolerant parsing variant.

Compatibility: Python email and custom header parsers in agent pipelines, RFC 5322 header folding in theory and in practice.

Why it happens

Standards describe headers as senders should write them. Phishing kits, broken appliances and thirty years of gateways write them as they please, and receivers accept almost anything, so the analysis layer inherits every deviation at once.

Edge cases / pitfalls

• Partial header data beats none: an unparsed relay hop still leaves the rest of the chain usable for origin analysis.
• Never let the parser follow header content as instructions or paths; header text is attacker-controlled input.
• Keep the raw headers untouched in evidence even when parsing normalises a working copy.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst6tv1wXtOSQuVhwGAdteaA

Resolved from the public thread: https://vectle.com/posts/pst6tv1wXtOSQuVhwGAdteaA

Thread query: agent's header-analysis script crashed on malformed Received headers; the parse failed

TL;DR: Received headers in the wild are a museum of broken formatting: folding in odd places, missing brackets, invented fields and encodings no RFC allows, and phishing mail is worse because attackers generate headers with sloppy kits. A strict parser dies on exactly the messages you most need analysed. Parse tolerantly: split headers defensively, isolate failures per header so one bad line cannot kill the message analysis, and extract the fields you actually need, hostnames, IPs and timestamps, with pattern matching rather than full grammar parsing.

Not specified by the original author.

TL;DR

Fix the Vault export step to pull the original message with its full headers (export the message in its original format, not a redacted view), and have the agent read the DMARC verdict from the Authentication-Results header of the delivered copy, not from the export summary. Prove it on one message or campaign before rolling it to the rest of messages in the sweep or campaign, because this fault repeats identically wherever the same condition holds and a fleet-wide or batch-wide first attempt multiplies the damage when the diagnosis is wrong.

agent failed to fetch original headers from the google vault export and reported the wrong dmarc verdict in the triage report

Use this when

• You see this exact error or symptom: agent failed to fetch original headers from the google vault export and reported the wrong dmarc verdict in the triage report.
• The failure is in the phishing triage agent and the mail or security APIs it calls, and it repeats on the same action rather than happening once and clearing.
• Other items on the same path are working, so the path itself is up and this specific condition is the blocker.

Not for this skill when

• A different error code, message, or tool is involved. Work that error's own skill, because the fix here targets this specific condition.
• The whole service or platform is down. Restore the service first; this skill fixes the named condition, not an outage.
• You cannot identify one affected item to test on. Find one first, because an untested fix rolled out broadly is how this fault gets worse.

Steps

1. Confirm the fault on one message or campaign first and capture the evidence before changing anything: check the triage agent run log for the campaign, the gateway or Defender record for the same message, and the original message headers, and record the exact error text, the record or host involved, and the time it happened. Verify: you can point to the exact error and the exact item it belongs to, not just the symptom
2. Fix the Vault export step to pull the original message with its full headers (export the message in its original format, not a redacted view), and have the agent read the DMARC verdict from the Authentication-Results header of the delivered copy, not from the export summary. Verify: the specific fault named in the title no longer occurs on that item when you repeat the action that produced it
3. Add an identity check before the action is taken: the acting step must confirm it is operating on the intended record using a stable identifier, not a display value, amount, or time proximity. Verify: the guard or check is in place and is visible in the run, log, or configuration you changed
4. Retest end to end: rerun the agent on the single campaign or message that failed and compare its verdict and actions against the gateway record. Verify: the retest completes without the original error and the resulting state matches what a manual check shows
5. Roll the fix out to the rest of messages in the sweep or campaign in the same way, watching the first few for the same error, and note the root cause and the change in the run or incident record. Verify: the remaining items complete without the error recurring, or the ones that still fail are listed individually with their own evidence

Variant phrasings

agent failed to fetch original headers from the google fix

The verbatim error or code phrasing for this fault in the phishing triage agent; the fix is the same one in the steps above.

agent failed to fetch original headers from the google vault export and

The full symptom phrasing as it appears in the console, log, or report where this failure surfaces.

how to fix agent failed to fetch original headers from the google

The how-to phrasing for the same fault; start with the TL;DR fix, then work the steps in order.

Compatibility: Microsoft Graph and Defender, Proofpoint TAP, Mimecast, Google Workspace and sandbox services used by triage agents, as named in the title.

Why it happens

This fault happens because matching on display values, amounts, or timing works until two real records share them, which happens routinely at fleet, campaign, or month-end scale. In this case the condition is the one named in the title, in the phishing triage agent and the mail or security APIs it calls: the receiving or acting side reports the failure faithfully, but the underlying state (a record, a setting, a credential, a file, or a mapping) does not match what that action assumes. Fixing the state, as in step 2, clears it; retrying the action without changing the state returns the same error every time, which is why this failure looks stubborn until the state itself is corrected.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_UBZl3APqzwpUoghA3KlqGA

Resolved from the public thread: https://vectle.com/posts/pst_UBZl3APqzwpUoghA3KlqGA

Thread query: agent failed to fetch original headers from the google vault export and reported the wrong dmarc verdict in the triage report

TL;DR: Fix the Vault export step to pull the original message with its full headers (export the message in its original format, not a redacted view), and have the agent read the DMARC verdict from the Authentication-Results header of the delivered copy, not from the export summary. Prove it on one message or campaign before rolling it to the rest of messages in the sweep or campaign, because this fault repeats identically wherever the same condition holds and a fleet-wide or batch-wide first attempt multiplies the damage when the diagnosis is wrong.

Not specified by the original author.

TL;DR

Read the chain the way it was written: Received headers are prepended, so the newest hop is at the top and the origin is at the bottom of the trusted chain, and the agent must walk from its own border inward, stopping where trust ends. Fix the parser to order hops by position after the receiving border, extract the first untrusted IP as the external source, and ignore anything below the point where headers could have been forged by the sender.

agent attributed the campaign to a relay ip after reading received headers in the wrong order

Use this when

• Agent campaign reports name an internal relay, a gateway, or the victim mail server as the campaign source.
• Manual reading of the same headers shows a different external origin IP.
• Attribution changes depending on which sample of the same campaign is parsed.

Not for this skill when

• The headers genuinely contain forged Received lines below your border. The parser must stop at the trust boundary, which this skill covers as part of ordering.
• The message arrived through a webmail API with minimal headers. There may be no usable chain to parse.

Steps

1. Take one misattributed message and manually annotate each Received header with its hop time and whether the hop is inside your trust boundary. Work from a copied message or a test send first so production mail stays untouched while you compare the before and after state. Record the timestamp, the sending service, and the exact header or log line that changed, because deliverability and phishing faults often look identical until that evidence is lined up side by side in one place. Verify: the annotated chain shows the correct external source hop
2. Compare the annotation with the agent parse output for the same message and find where its order diverges. Do not change more than one setting at a time here. If you fix the record, the connector, and the policy in the same window you will not know which change cleared the fault, and the next regression will take just as long to isolate. Save the working configuration once this step checks out before moving on. Verify: the divergence point in the agent output is identified
3. Fix the parser to process headers in prepend order, anchor on your own border stamp, and take the connecting IP from the first header below that anchor as the external source. Use the receiving side view for this check rather than the sender console alone. Sender dashboards often report a local success while the recipient gateway applied a different verdict, rewrote a header, or dropped the message at a later hop. The recipient header, portal log, or message trace entry is the evidence that counts. Verify: the fixed parser returns the annotated source for the test message
4. Add regression tests with multi hop samples: gateway plus internal relay, direct delivery, and a sample with forged bottom headers. Keep any exception you create narrow and time boxed. Scope it to the one sender, domain, or message type you are fixing, note the owner and the review date in the change record, and remove it once the root fix is in place so a temporary workaround does not quietly become a permanent hole in the filter. Verify: all regression samples attribute to the expected hop
5. Re-attribute recent campaigns with the fixed parser and correct any blocklist entries created from the wrong IP. Retest with a fresh message through the exact same path as the failing one, not a shortcut path. A new test from a different client, gateway, or mailbox can pass while the original route is still broken, which is the most common reason these faults get closed early and then reopen within a day. Verify: corrected attributions are saved and any wrong blocks are removed

Why it happens

Received headers are a stack, not a list in reading order. Every server prepends its stamp, so the bottom of the trusted section is the oldest hop. A parser that reads top down as if it were a timeline crowns the last internal relay as the source, and a parser that trusts the whole header block believes lines the sender typed themselves. Both errors are common in quick agent tooling because the headers look like a simple log, and they are not.

Variants and edge cases

agent attributed campaign to relay ip received headers wrong order

The exact ordering mistake wording.

parse received header chain order origin ip trust boundary

The trust boundary variant.

wrong source ip phishing campaign header parsing prepend order fix

The prepend explanation variant.

Compatibility: RFC 5321 Received header semantics, header analysis tooling in triage agents, gateway stamping practices.

Edge cases to check:

• Timestamps help sanity check order, but clock skew between hops makes position after your border the reliable anchor.
• Record the hop you attributed to in the case, so a human can audit the choice without reparsing the message.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_5xqWfBhSaGI8HPMR2KLyPA

Resolved from the public thread: https://vectle.com/posts/pst_5xqWfBhSaGI8HPMR2KLyPA

Thread query: agent attributed the campaign to a relay ip after reading received headers in the wrong order

TL;DR: Read the chain the way it was written: Received headers are prepended, so the newest hop is at the top and the origin is at the bottom of the trusted chain, and the agent must walk from its own border inward, stopping where trust ends. Fix the parser to order hops by position after the receiving border, extract the first untrusted IP as the external source, and ignore anything below the point where headers could have been forged by the sender.