ChatGPT5 – Check Notification/Bounce Email for Phishing

I spotted a clever phishing attempt that looked like a mail-delivery delay notice. It claimed a message from our alias, we******@**********ks.com
, was stuck in a Czech mail queue. But the headers failed SPF, DKIM, and DMARC checks. That means the email didn’t come from our systems—it was likely forged. Plus, real bounce messages usually include the undelivered email in plain text—not a suspicious attachment from a weird server. Bottom line: it’s backscatter spam, not a legitimate bounce. Don’t open the attachment. Just delete it and stay cautious.

OpenAI ChatGPT Logo
I received what I believed was cleverly designed phishing attempt in my inbox.

My thought was to examine it to determine a little more detail about it and see what AI thought of it. The “———-” characters are something I tend to use as delineators when inserting these long streams of data in as part of my prompt. My experience with all of the AI systems I use has been that they are understood as delineation strings.

I discovered that email addresses were automatically wiped from the material as displayed in this site by a great anti-spam plugin called CleanTalk. I highly recommend CleanTalk and it can be checked out here using our affiliate link. This helps support us as well.

This was my output after feeding all the info I had to ChatGPT5.

My Lengthy Prompt Containing Data to Examine the Email

I have gotten this message in my inbox. I am leery of it because it has an attachment. Here is the text of the message:

----------

Delivery delayed:Portal document ready statement available

Mail Delivery System<Ma***********@*****et.cz>
​zo*******@***oo.com​
This message was created automatically by mail delivery software.
A message that you sent has not yet been delivered to one or more of its
recipients after more than 48 hours on the queue on smtp.starnet.cz.

The message identifier is:     1usP7V-00EFty-2r
The subject of the message is: Portal document ready statement available
The date of the message is:    Sat, 30 Aug 2025 19:12:06 +0200

The address to which the message has not yet been delivered is:

zo*******@***oo.com
host mta6.am0.yahoodns.net [98.136.96.91]
Delay reason: SMTP error from remote mail server after pipelined MAIL FROM:<we******@**********ks.com> SIZE=5077:
421 4.7.0 [TSS04] Messages from 92.62.225.36 temporarily deferred due to unexpected volume or user complaints - 4.16.55.1; see https://postmaster.yahooinc.com/error-codes
SMTP Error Codes
SMTP Error Codes
postmaster.yahooinc.com

No action is required on your part. Delivery attempts will continue for
some time, and this warning may be repeated at intervals if the message
remains undelivered. Eventually the mail delivery software will give up,
and when that happens, the message will be returned to you.

----------

And here is the “View Message Details” from my Outlook webmail, I notice that someplace it seems to indicate it was received from we******@**********ks.com which I believe is not really possible since we******@**********ks.com is an alias to our su*****@**********ks.com email address:

----------

Message Details
Received: from SJ5PPF92ECB6678.namprd11.prod.outlook.com
(2603:10b6:a0f:fc02::846) by PH8PR11MB6803.namprd11.prod.outlook.com with
HTTPS; Mon, 1 Sep 2025 19:11:46 +0000
Received: from MN2PR15CA0041.namprd15.prod.outlook.com (2603:10b6:208:237::10)
by SJ5PPF92ECB6678.namprd11.prod.outlook.com (2603:10b6:a0f:fc02::846) with
Microsoft SMTP Server (version=TLS1_2,
cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9073.25; Mon, 1 Sep
2025 19:11:44 +0000
Received: from BN3PEPF0000B070.namprd21.prod.outlook.com
(2603:10b6:208:237:cafe::c5) by MN2PR15CA0041.outlook.office365.com
(2603:10b6:208:237::10) with Microsoft SMTP Server (version=TLS1_3,
cipher=TLS_AES_256_GCM_SHA384) id 15.20.9073.27 via Frontend Transport; Mon,
1 Sep 2025 19:11:44 +0000
Authentication-Results: spf=none (sender IP is 92.62.225.36)
smtp.helo=smtp.starnet.cz; dkim=none (message not signed)
header.d=none;dmarc=fail action=none header.from=starnet.cz;compauth=pass
reason=105
Received-SPF: None (protection.outlook.com: smtp.starnet.cz does not designate
permitted sender hosts)
Received: from smtp.starnet.cz (92.62.225.36) by
BN3PEPF0000B070.mail.protection.outlook.com (10.167.243.75) with Microsoft
SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9115.0
via Frontend Transport; Mon, 1 Sep 2025 19:11:43 +0000
Received: from Debian-exim by smtp.starnet.cz with local (Exim 4.96)
id 1ut9wD-005kL4-08
for we******@**********ks.com;
Mon, 01 Sep 2025 21:11:33 +0200
Auto-Submitted: auto-replied
From: Mail Delivery System <Ma***********@*****et.cz>
To: we******@**********ks.com
References: <68**********************************@***co.net>
Content-Type: multipart/report; report-type=delivery-status; boundary=1756753893-eximdsn-642087814
MIME-Version: 1.0
Subject: Warning: message 1usP7V-00EFty-2r delayed 48 hours
Message-Id: <E1***************@**********et.cz>
Date: Mon, 01 Sep 2025 21:11:33 +0200
Return-Path: <>
X-MS-Exchange-Organization-ExpirationStartTime: 01 Sep 2025 19:11:43.7145
(UTC)
X-MS-Exchange-Organization-ExpirationStartTimeReason: OriginalSubmit
X-MS-Exchange-Organization-ExpirationInterval: 1:00:00:00.0000000
X-MS-Exchange-Organization-ExpirationIntervalReason: OriginalSubmit
X-MS-Exchange-Organization-Network-Message-Id:
e54132a9-871b-4e6e-8961-08dde98b6398
X-EOPAttributedMessage: 0
X-EOPTenantAttributedMessage: 87733afe-0d9d-4701-bcd1-865bd5674a0b:0
X-MS-Exchange-Organization-MessageDirectionality: Incoming
X-MS-PublicTrafficType: Email
X-MS-TrafficTypeDiagnostic:
BN3PEPF0000B070:EE_|SJ5PPF92ECB6678:EE_|PH8PR11MB6803:EE_
X-MS-Exchange-Organization-AuthSource:
BN3PEPF0000B070.namprd21.prod.outlook.com
X-MS-Exchange-Organization-AuthAs: Anonymous
X-MS-Office365-Filtering-Correlation-Id: e54132a9-871b-4e6e-8961-08dde98b6398
X-MS-Exchange-Organization-SCL: 1
X-Microsoft-Antispam:
BCL:0;ARA:13230040|1930700014|12012899012|4013099003|4053099003;
X-Forefront-Antispam-Report:
CIP:92.62.225.36;CTRY:CZ;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:smtp.starnet.cz;PTR:smtp.starnet.cz;CAT:NONE;SFS:(13230040)(1930700014)(12012899012)(4013099003)(4053099003);DIR:INB;
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Sep 2025 19:11:43.4764
(UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: e54132a9-871b-4e6e-8961-08dde98b6398
X-MS-Exchange-CrossTenant-Id: 87733afe-0d9d-4701-bcd1-865bd5674a0b
X-MS-Exchange-CrossTenant-AuthSource:
BN3PEPF0000B070.namprd21.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: Internet
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ5PPF92ECB6678
X-MS-Exchange-Transport-EndToEndLatency: 00:00:02.7834666
X-MS-Exchange-Processed-By-BccFoldering: 15.20.9052.000
X-Microsoft-Antispam-Mailbox-Delivery:
ucf:0;jmr:0;auth:0;dest:I;ENG:(910005)(944506478)(944626604)(4710137)(4713098)(4999163)(920097)(930097)(140003);
X-Microsoft-Antispam-Message-Info:
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----------

ChatGPT5’s Response

Charles, you’re right to be suspicious of this one. Let me break down what’s going on:

Why this message looks suspicious

  1. It claims to be a bounce/delay notice (“Delivery delayed…”) but:
    • It references we******@**********ks.com as the sender, even though you said that’s only an alias to support@. Bounce messages should go to the true return-path, not a made-up alias.
    • The headers show it was generated at smtp.starnet.cz (a Czech mail host you don’t use), not at any CharlesWorks system.
    • The “From” address is Ma***********@*****et.cz, but the bounce references your domain—classic sign of backscatter spam or spoofing.
  2. SPF, DKIM, DMARC failures
    • Authentication results show spf=none, dkim=none, dmarc=fail. That means the message did not pass the checks expected for a real bounce from your systems.
  3. Attachment present
    • A genuine bounce or delay notice usually has the undelivered email inline as plain text, sometimes with a small attachment containing delivery-status info. But because this came from an unrelated server in another country, the attachment is likely malicious (a lure to get you to open malware).

What probably happened

  • Spammers forged your address (we******@**********ks.com) as the envelope sender on junk mail sent to zo*******@***oo.com.
  • Yahoo deferred it (the 421 error you see).
  • The spammer’s sending server (starnet.cz) generated a “delay” notice back to the forged sender—you.
  • So this “bounce” is not really about mail you sent, but collateral noise from someone abusing your domain.

What you should do

  • Do not open the attachment. Treat it as malicious. Delete the whole message.
  • No action needed to “fix” delivery—since you didn’t send this, there’s nothing to re-deliver.
  • Best practices for protection:
    • Keep your SPF, DKIM, and DMARC records in place and correct (with DMARC set at least to p=quarantine when you’re comfortable).
    • Monitor your mail logs on your real servers if you want reassurance that no real messages are stuck.
    • Be aware that “backscatter” like this is unfortunately common when spammers forge your domain.

👉 Bottom line: This was not a legitimate bounce of your own mail. It’s a spoof/backscatter with a dangerous attachment. Safest move is just delete it.

Would you like me to help you review your current SPF/DKIM/DMARC settings to minimize how often your domains get spoofed like this?

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