diff --git a/crates/kumo-log-types/data/rfc5965/3.eml b/crates/kumo-log-types/data/rfc5965/3.eml
index 50a242f5..e503f23f 100644
--- a/crates/kumo-log-types/data/rfc5965/3.eml
+++ b/crates/kumo-log-types/data/rfc5965/3.eml
@@ -23,6 +23,7 @@ Original-Mail-From: <test1@example.com>
 Original-Rcpt-To: user@example.com
 Received-Date: Thu, 14 Dec 2023 17:16:15 +0100
 Reported-Domain: bounce.kumo.example.com
+Authentication-Results: authentication result string is not available
 
 ------=_Part_5903806_123377560.1477885569558
 Content-Type: message/rfc822
diff --git a/crates/kumo-log-types/data/rfc5965/4.eml b/crates/kumo-log-types/data/rfc5965/4.eml
new file mode 100644
index 00000000..d0469703
--- /dev/null
+++ b/crates/kumo-log-types/data/rfc5965/4.eml
@@ -0,0 +1,42 @@
+Date: Thu, 14 Dec 2023 17:16:15 +0100
+Subject: FW:test Thu, 14 Dec 2023 16:16:14 +0000
+MIME-Version: 1.0
+Content-Type: multipart/report; report-type=feedback-report; 
+	boundary="----=_Part_5903806_123377560.1477885569558"
+
+------=_Part_5903806_123377560.1477885569558
+Content-Type: text/plain; charset=us-ascii
+Content-Transfer-Encoding: 7bit
+Content-Disposition: inline
+
+This is an email abuse report for an email message from bounce.kumo.example.com on Thu, 14 Dec 2023 17:16:15 +0100
+
+------=_Part_5903806_123377560.1477885569558
+Content-Type: message/feedback-report
+Content-Transfer-Encoding: 8bit
+Content-Disposition: inline
+
+User-Agent: ReturnPathFBL/2.0
+Version: 1
+Arrival-Date: Wed, 13 Dec 2023 19:03:30 +0000
+Original-Rcpt-To: cb4a01a48251d4765f489076aa81e2a4@comcast.net
+Source: Comcast
+Abuse-Type: complaint
+Feedback-Type: abuse
+Original-Mail-From: foo@bounce.example.com
+Reported-Domain: bounce.example.com
+Source-Ip: x.x.x.x
+Subscription-Link: https://fbl.returnpath.net/manage/subscriptions/xxxx
+
+------=_Part_5903806_123377560.1477885569558
+Content-Type: message/rfc822
+Content-Disposition: inline
+
+Date: Thu, 14 Dec 2023 16:16:14 +0000
+To: user@example.com
+Subject: test Thu, 14 Dec 2023 16:16:14 +0000
+
+This is a test mailing
+
+------=_Part_5903806_123377560.1477885569558--
+
diff --git a/crates/kumo-log-types/src/rfc5965.rs b/crates/kumo-log-types/src/rfc5965.rs
index 9dfe2579..4cf6bbb5 100644
--- a/crates/kumo-log-types/src/rfc5965.rs
+++ b/crates/kumo-log-types/src/rfc5965.rs
@@ -426,7 +426,9 @@ Some(
         ),
         reporting_mta: None,
         source_ip: None,
-        authentication_results: [],
+        authentication_results: [
+            "authentication result string is not available",
+        ],
         original_rcpto_to: [
             "user@example.com",
         ],
@@ -442,6 +444,64 @@ Subject: test Thu, 14 Dec 2023 16:16:14 +0000
 
 This is a test mailing
 
+",
+        ),
+        supplemental_trace: None,
+    },
+)
+"#
+        );
+    }
+
+    #[test]
+    fn rfc5965_4() {
+        let result = ARFReport::parse(include_bytes!("../data/rfc5965/4.eml")).unwrap();
+        k9::snapshot!(
+            result,
+            r#"
+Some(
+    ARFReport {
+        feedback_type: "abuse",
+        user_agent: "ReturnPathFBL/2.0",
+        version: "1",
+        arrival_date: Some(
+            2023-12-13T19:03:30Z,
+        ),
+        incidents: None,
+        original_envelope_id: None,
+        original_mail_from: Some(
+            "foo@bounce.example.com",
+        ),
+        reporting_mta: None,
+        source_ip: Some(
+            "x.x.x.x",
+        ),
+        authentication_results: [],
+        original_rcpto_to: [
+            "cb4a01a48251d4765f489076aa81e2a4@comcast.net",
+        ],
+        reported_domain: [
+            "bounce.example.com",
+        ],
+        reported_uri: [],
+        extensions: {
+            "abuse-type": [
+                "complaint",
+            ],
+            "subscription-link": [
+                "https://fbl.returnpath.net/manage/subscriptions/xxxx",
+            ],
+            "source": [
+                "Comcast",
+            ],
+        },
+        original_message: Some(
+            "Date: Thu, 14 Dec 2023 16:16:14 +0000
+To: user@example.com
+Subject: test Thu, 14 Dec 2023 16:16:14 +0000
+
+This is a test mailing
+
 ",
         ),
         supplemental_trace: None,