Do not trust fake "Messages Not Delivered Due To Server Interruptions" emails

What kind of email is "Messages Not Delivered Due To Server Interruptions"?

Our inspection of the "Messages Not Delivered Due To Server Interruptions" email revealed that it is spam. This phishing letter aims to trick recipients into disclosing their email account credentials by making false claims regarding undelivered messages.

"Messages Not Delivered Due To Server Interruptions" email scam overview

The spam email with the subject "Mail Delivery: [7] Undelivered incoming messages" (may vary) informs the recipient that messages have failed to reach their inbox due to server interruptions. Immediate action is required to avoid data loss (i.e., to prevent the loss of the undelivered emails).

The letter instructs to click the "Email Account Settings" button in order to review the pending messages and to fix any bugs. The recipient is warned that if they fail to do so, they may also experience interruptions with the sign-in process to their email account.

As mentioned in the introduction, this letter is fake, as are all its claims. When we followed the link presented in this spam message (i.e., clicked the button), it resulted in a redirect to a phishing website. The page was disguised as an email account sign-in page.

Log-in credentials (i.e., email account addresses and corresponding passwords) entered into this phishing site will be disclosed to the cyber criminals behind this spam campaign. Not only can the criminals steal the exposed email account with this information, but they may also hijack the content registered through it.

Stolen content can be variously misused for profit, to elaborate – finance-related accounts (e.g., online banking, e-commerce, digital wallets, etc.) can be used to make fraudulent transactions or online purchases.

Scammers can also steal the identities of social account owners (e.g., emails, social networking, social media, etc.) and ask their contacts/friends/followers for loans, promote scams, and even distribute malware by sharing malicious files or links.

In summary, the threats posed by a spam email like "Messages Not Delivered Due To Server Interruptions" include system infections, severe privacy issues, financial losses, and identity theft.

If you have already disclosed your log-in credentials – change the passwords of all potentially exposed accounts and contact their official support without delay.

Phishing spam campaign examples

We have analyzed thousands of spam emails; "Product Availability Confirmation", "Measures To Strengthen Server Security", "Incoming Mails Have Been Restricted", and "Documents Inquiry" are just some examples of ones used for phishing.

Various scams are promoted using emails, including phishing, sextortion, tech support, lotteries, inheritances, etc. In addition to deceptive content, this mail is used to proliferate malware (e.g., trojans, ransomware, cryptominers, etc.). These letters can even be disguised as messages from legitimate service providers, companies, corporations, institutions, authorities, and other entities.

Due to how prevalent spam mail is, we highly recommend exercising caution with incoming emails, PMs/DMs, SMSes, and other messages.

How do spam campaigns infect computers?

Spam emails can contain infectious files as attachments or download links. These files can be archives (RAR, ZIP, etc.), executables (.exe, .run, etc.), documents (Microsoft OneNote, Microsoft Office, PDF, etc.), JavaScript, and so forth.

When a virulent file is executed, run, or otherwise opened – the malware download/installation process is triggered. For example, Microsoft OneNote documents require users to click on embedded files/links to start downloading/installing this software, while Office files infect devices by executing malicious macro commands.

How to avoid installation of malware?

We strongly advise against opening attachments or links found in suspicious mail, as they can be malicious and cause infections. It is essential to use Microsoft Office versions released after 2010 since they have the "Protected View" mode that prevents automatic macro execution.

However, malware is not proliferated exclusively via spam mail. Therefore, we recommend downloading only from official and verified channels. Additionally, all programs must be activated and updated using legitimate functions/tools, as illegal activation tools ("cracks") and third-party updaters may contain malware.

Another recommendation is to exercise caution while browsing since fake and dangerous online content typically appears ordinary and harmless.

We must stress that having a reputable anti-virus installed and kept up-to-date is paramount to device and user safety. This software must be used to run regular system scans and to remove detected threats and issues. If you've already opened malicious attachments, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate infiltrated malware.

Text presented in the "Messages Not Delivered Due To Server Interruptions" spam email letter:

Subject: Mail Delivery: [7] Undelivered incoming messages

Dear -,

Your incoming messages has been not delivered due to server interruptions.
This could lead to loss of data and information, immediate action is required.
Go to Email account settings below to review undelivered mails and fix bugs.

Email Account Settings

Failure to review your account may cause login interruption.

-
Copyright © 2023 All Rights Reserved.

Screenshot of the phishing website promoted through this spam campaign:

Another example of an undelivered mail-themed spam promoting a phishing site:

Text presented within:

Subject: Email Notification: You have (3) pending messɑges

 

Your email account  ******** has Undelivered messages. Resolve issue to avoid termination of mails.

Dear ********,

You have 3 important message that were not successfully delivered to your Inbox

[ ******** ], as a result of inbox malfunction and lack of mail validations
RESΟLVE

Note: If the above actions are not performed messages will be deleted within hours of your reception of the mail

Sincerely,
******** IT Administrator for ********

Screenshot of the promoted phishing site:

Instant automatic malware removal:

Manual threat removal might be a lengthy and complicated process that requires advanced IT skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:

By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. To use full-featured product, you have to purchase a license for Combo Cleaner. 7 days free trial available. Combo Cleaner is owned and operated by RCS LT, the parent company of PCRisk.com.

Types of malicious emails:

If you opened an attachment or downloaded a file from a suspicious email, run a full system scan with Combo Cleaner. If you only received the email and didn't engage with it, you don't need to scan anything - just identify the scam and delete it. The full procedure below covers both situations and what to do if you already clicked, replied, or sent money.

Credential theft Phishing emails

Fake login pages disguised as PayPal, Microsoft, Apple, banks, or social networks. The email pushes a link to a near-perfect copy of the real login screen. The moment you type your username and password, the attacker has them.

Common subject lines

• "Action required: confirm your account"
• "Your password expires today"
• "Unusual sign-in attempt detected"
• "Verify your billing information"

Malware delivery Emails with malicious attachments

Trojans hidden inside fake invoices, faxes, shipping confirmations, or Office documents. Opening the attachment runs the payload and infects the system - often with an info-stealer or remote-access trojan.

Common subject lines

• "Invoice INV-2026-XXXX attached"
• "Fax received - 3 pages"
• "Your shipping document is ready"
• "Voicemail from +1-XXX-XXX-XXXX"

Extortion Sextortion emails

Fake claims of webcam recordings demanding cryptocurrency. Almost always a bluff: the attacker pulls a real password from an old data breach to make the threat look credible, then claims to have video of you. They have no recording and no access.

Common subject lines

• "I know your password is XXXX"
• "Your account has been hacked"
• "I have recorded you - 48 hours to pay"
• "You have been compromised"

Callback fraud Refund & callback scams

"Your subscription was renewed for $499 - call to cancel." Norton, McAfee, Geek Squad, PayPal, and Wells Fargo variants are all common. There's no real subscription. The phone number in the email connects directly to the scammer, who walks you through "refunding" yourself - which is actually them stealing money from your bank.

Common subject lines

• "Norton subscription auto-renewed - $499.99"
• "McAfee Total Protection invoice"
• "Geek Squad order confirmation"
• "Your PayPal payment is being processed"

Credential theft Account suspension & verification scams

"Your account will be deleted in 24 hours - verify now." The artificial deadline is the whole point: it pressures you to click before checking details. The "verify" link goes to a phishing page styled to look like the real provider.

Common subject lines

• "Your account will be deleted in 24 hours"
• "Suspicious activity detected - verify now"
• "Final warning: account closure"
• "Action required to keep your account active"

Mixed payload Delivery & package scams

Fake DHL, USPS, UPS, or FedEx tracking, customs fees, or "package undeliverable" notices. Targets anyone expecting a parcel - the timing alone catches many people. The link hides either phishing (asking for card details to "release" the package) or a malware download.

Common subject lines

• "Your DHL package is held at customs"
• "USPS - delivery attempt failed"
• "FedEx tracking update - action required"
• "Pay $2.99 redelivery fee to release your parcel"

Remote access Tech support scams

Fake Microsoft, Apple, or "Windows Defender" security alerts pushing a phone number. Real Microsoft and Apple never email a phone number to call. The number connects you to a scammer who asks for remote access to "fix" the imaginary problem and then demands payment.

Common subject lines

• "Microsoft Defender expired - renew now"
• "Apple ID security alert"
• "Critical: virus detected on your PC"
• "Windows license expired - call now"

Wire fraud Advance-fee scams

Inheritance, lottery wins, romance, or business deals that ask for a small fee to release a much larger sum. The classic "Nigerian prince" 419 family of frauds. Once you pay the first fee, more fees appear (taxes, lawyer, transfer charges) until you stop paying. The promised money never exists.

Common subject lines

• "Inheritance from a relative you didn't know about"
• "You won the international lottery"
• "URGENT - business proposal worth $XX million"
• "Compensation fund release for fraud victims"

Wire fraud Business email compromise (BEC)

CEO impersonation asking employees to wire money or buy gift cards, or fake supplier invoices with newly "updated" bank details for payment redirection. The email often spoofs a real internal executive's display name and uses an external lookalike domain.

Common subject lines

• "Quick task - need you to buy gift cards"
• "Updated banking details for invoice payment"
• "Wire transfer request - urgent"
• "Are you available?" (CEO impersonation opener)

How to spot a malicious email?

Phase 1~ 2 min

Spot - identify the red flags

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1

Check the sender's actual address, not the display name

30 sec

The display name (the human-readable part) is trivial to fake. Always check the full address that comes after it. Common red flags:

• Domain mismatch - service@paypa1.com, support@micros0ft-help.com, look-alike domains using digits or extra hyphens
• Free-email impersonation - any "official" message from a bank, courier, or platform sent from a @gmail.com, @outlook.com, or @yahoo.com address
• Reply-To mismatch - the From address looks legitimate but Reply-To points somewhere completely different

Why this matters

Real companies own their domains and send mail from them. A "DHL" message from a Gmail address is never legitimate, regardless of how convincing the body looks.

2

Watch for urgency, threats, and generic greetings

30 sec

Scams almost always rush you. The point is to make you act before you think. Treat any of the following as a strong signal:

• "Your account will be deleted in 24 hours"
• "Final notice" / "Immediate action required"
• "Dear Customer" or "Dear User" instead of your real name
• Threats of fines, account closure, legal action, or arrest
• Promises of refunds, prizes, or money you didn't earn
• Spelling and grammar mistakes in messages claiming to come from a major brand

3

Hover over every link before clicking

30 sec

On a desktop, hover the mouse over the link without clicking. The real destination shows in the bottom-left status bar of your browser or email client. On a phone, long-press the link to preview the URL.

• Real Microsoft, PayPal, or bank links go to those exact domains, not redirects through unrelated sites
• Shortened URLs (bit.ly, tinyurl, t.co) hide the real destination - never click them in unsolicited mail
• The visible link text and the actual URL must match - mismatches are the single biggest phishing red flag

Pro tip

When in doubt, don't click the link. Open a new browser tab and type the company's address yourself, then log in normally. If there really is an issue with your account, you'll see it there.

4

Treat unexpected attachments as hostile

30 sec

If you didn't ask for the file, don't open it - even if it appears to come from someone you know. Categories that should never be opened from email without verification through another channel:

• .exe, .scr, .iso, .img, .vbs, .bat - executables, never legitimate attachments
• .docx, .xlsx, .pptx with "Enable macros" prompts - the macros run the malware
• .pdf with "Click here to view" buttons - usually a phishing redirect, not a real document
• .zip, .rar, .7z archives, especially password-protected ones - the password defeats the email scanner

Phase 2~ 2 min

Report and delete - if you haven't engaged

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If you only received the email and didn't reply, click, or open anything, the steps below are all you need. Your computer is not infected.

5

Don't reply, don't click "unsubscribe"

30 sec

Replying confirms your address is real and monitored, which gets you added to higher-value scam lists. The "unsubscribe" link in a scam message is rarely a real opt-out - it usually leads to a phishing page or downloads a tracking pixel.

Instead, mark the message as junk or phishing inside your email client (this trains the spam filter), then block the sender.

6

Report the scam to your email provider and authorities

1 min

Inside your email client:

• Gmail: open the message → ⋮ menu → Report phishing
• Outlook / Outlook.com: ⋯ menu → Report → Report phishing
• Apple Mail / iCloud: Move to Junk, then forward to reportphishing@apple.com

Forward or report to authorities:

• International: forward to reportphishing@apwg.org
• United States: ic3.gov (FBI)
• United Kingdom: forward phishing emails to report@phishing.gov.uk (NCSC SERS); for financial loss report at reportfraud.police.uk (Report Fraud, the successor to Action Fraud; 0300 123 2040)
• Canada: antifraudcentre.ca
• Australia: scamwatch.gov.au
• EU: your national CERT - find yours via the ENISA CSIRT map

After reporting, delete the email and empty the Trash folder so you don't accidentally open it later.

Phase 3~ 10–60 min

Recover - if you already engaged with the scam

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Pick the step below that matches what you did. If multiple apply, work through them in the order they appear - the steps are arranged from lowest to highest risk.

7

You only clicked a link (didn't enter anything or download anything)

Scenario: clicked link only10 min

Close the page right away. Don't enter any information, even if the page looks legitimate.

• Clear your browser cache and cookies for the last hour - Chrome/Edge: Ctrl+Shift+Del → Last hour → check Cookies and Cached files
• Run a quick scan with Combo Cleaner in case the page tried to drop a file silently (drive-by download)
• Update your browser to the latest version - most drive-by exploits target outdated browsers
• Watch for new browser pop-ups, redirects, or unfamiliar notifications over the next few days

Why this matters

Modern browsers block most drive-by attacks, but a single click on a phishing page can still be enough on an outdated browser or unpatched plugin. A quick scan catches anything that landed silently.

8

You opened an attachment or downloaded a file - run a full malware scan

Scenario: opened attachment⚠ Highest risk60–90 min

Opening an attachment is the most common path to actual infection. Treat the system as compromised until the scans below come back clean. Work through these sub-steps in order:

8.1Disconnect from the network

Unplug Ethernet and turn off Wi-Fi. If the attachment was an info-stealer or remote-access trojan, this stops it from sending data out or receiving commands. Keep the network off until you've booted into Safe Mode (next step) - you'll reconnect there briefly to download the scanners.

8.2Boot into Safe Mode with Networking, then download the scanners

Windows 11: Settings → System → Recovery → Advanced startup → Restart now → Troubleshoot → Advanced options → Startup Settings → Restart → press 5 or F5.

Windows 10: hold Shift, click Power → Restart → Troubleshoot → Advanced options → Startup Settings → Restart → press F5.

Once Safe Mode has loaded, turn Wi-Fi back on and download Combo Cleaner (used in 8.4) and Microsoft Safety Scanner (used in 8.5). Safe Mode loads only minimal drivers, so most malware can't auto-run while you're getting the tools. Save both installers to your Desktop.

8.3Run Microsoft Defender Offline

Reboot to normal Windows. Open Windows Security → Virus & threat protection → Scan options. Select Microsoft Defender Antivirus (offline scan) and click Scan now. The PC restarts into a stripped-down environment and scans the disk before Windows fully loads - this is what catches rootkits and bootkits.

Recommended antivirus

Combo Cleaner

VB100 certified. Includes anti-trojan, registry/persistence scanning, and anti-spyware in one pass. The 7-day free trial is available.

Download Combo Cleaner

8.4Run a full Combo Cleaner scan

Install Combo Cleaner and run a full system scan (not the quick scan). Let it complete fully, review what it found, and apply the recommended actions. Combo Cleaner will quarantine known trojans and remove their persistence in the registry.

8.5Run Microsoft Safety Scanner as a second-opinion scan

Download Microsoft Safety Scanner (MSERT.exe). The binary expires every 10 days, which means every download has the latest signatures. Run a full scan after Combo Cleaner to catch anything one engine alone might miss.

8.6Reset browsers and clear notification permissions

Many email-borne trojans drop adware that hijacks browsers. Reset each browser you use:

Chrome: chrome://settings/reset → Restore settings to their original defaults. Then chrome://settings/content/notifications - remove unfamiliar sites.

Edge: edge://settings/reset. Then edge://settings/content/notifications.

Firefox: about:support → Refresh Firefox.

8.7Re-enable Defender, Tamper Protection, and update everything

Open Windows Security → Virus & threat protection → Manage settings and confirm Real-time protection, Cloud-delivered protection, and Tamper Protection are all on. Then run Settings → Windows Update → Check for updates and update browsers and applications.

Important

If the scans keep finding new threats on each run, or files reappear after deletion, you may have a deeper compromise that needs a clean Windows reinstall. See pcrisk's full manual malware removal guide for the extended procedure (Process Explorer, Autoruns, hosts file inspection).

9

You entered credentials on a fake login page

Scenario: shared password⚠ Act fast20 min

Assume the attacker has your password and is using it right now. Speed matters.

1. Change the password from a different, known-clean device (your phone is fine if it's not infected). Don't reuse the old password anywhere else.
2. Enable two-factor authentication if you haven't already. Prefer an authenticator app or hardware key over SMS.
3. Sign out of all sessions - most platforms have a "sign out everywhere" option in security settings, which kicks the attacker out.
4. Review recent activity - look for unfamiliar logins, new devices, forwarding rules, or app permissions. Remove anything you don't recognize.
5. Check your other accounts - if you reused that password anywhere else, change it there too. Check your exposure at haveibeenpwned.com.
6. Update security questions - the attacker may have seen the answers in your account profile.

Why email comes first

If you only have time to change one password, change your primary email password - it's the recovery hub for every other account. An attacker who controls your email can reset everything else.

10

You sent money or shared bank, card, or ID details

Scenario: financial loss⚠ Contact bank now30 min

Time is the single biggest factor in recovering money. Banks can sometimes recall a wire or reverse a card transaction within the first few hours.

1. Call your bank or card issuer immediately. Use the number on the back of the card, not any number from the scam email. Ask them to freeze the card, reverse the transaction if possible, and flag the account for fraud monitoring.
2. If you sent a wire transfer or used a money-transfer service (Western Union, MoneyGram, Zelle, Wise), call them directly and request a recall. Some can be reversed within minutes if reported fast.
3. If you sent cryptocurrency or gift cards, recovery is unlikely - but report it anyway, since law enforcement tracks these patterns.
4. File a police report. You'll need the report number for any insurance, bank, or credit-bureau claim. Save the report number.
5. File with the right authority for your country:
   • US: ic3.gov + reportfraud.ftc.gov
   • UK: reportfraud.police.uk (Report Fraud, the successor to Action Fraud; 0300 123 2040)
   • Canada: antifraudcentre.ca
   • Australia: scamwatch.gov.au
   • EU: your national CERT or police cybercrime unit
6. Set fraud alerts on all major credit bureaus if you shared any ID details. US: Equifax, Experian, TransUnion. UK: Experian, Equifax, TransUnion (Cifas Protective Registration is a stronger option).
7. Save all evidence - the original email (with full headers), screenshots of the fake site, transaction records, any phone numbers or chat logs.

Phase 4~ 15 min + 30 days

Verify & monitor

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11

Final scan and startup-app check

15 min

Reconnect to the network and run one final full scan with Combo Cleaner, followed by a Windows Defender quick scan. Then open Task Manager (Ctrl + Shift + Esc) and switch to Startup apps - disable anything unfamiliar.

Make sure Windows, browsers, and any applications you use are fully up to date. The infection vector that worked on you once usually involves outdated software.

12

Monitor accounts and credit for 30 days

5 min/day · 30 days

Most fraud follow-ups land in the first month. Until that window closes, keep watching:

• Bank and card statements - daily for the first week, then weekly
• Email - watch for password-reset confirmations or login alerts you didn't trigger
• Credit report - US: free at annualcreditreport.com; UK: Experian, Equifax, TransUnion all have free tiers
• Breach alerts - sign up at haveibeenpwned.com to be notified when your email appears in new leaks

If anything new appears in any of those, treat it as a continuing compromise: change passwords again, contact the bank again, and update the police report.

Important: If you didn't click anything, didn't reply, and didn't open any attachment, your computer is not infected - just delete the email and move on. If you opened an attachment or downloaded a file, run an automated scan with Combo Cleaner and Windows Defender and stop there. That path catches the vast majority of email-borne malware without the risk of breaking Windows by deleting the wrong file.

Frequently Asked Questions (FAQ)

Why did I receive this email?

Spam emails are not personal. They are distributed in massive operations – therefore, thousands of users receive identical messages.

I have provided my personal information when tricked by this spam email, what should I do?

If you have disclosed your log-in credentials – immediately change the passwords of all possibly compromised accounts and inform their official support. And if you've provided other private information (e.g., ID card details, credit card numbers, etc.) – contact the appropriate authorities without delay.

I have read a spam email but didn't open the attachment, is my computer infected?

No, merely opening an email will not initiate system infection processes. Malware download/installation processes are initiated when malicious attachments or links are opened.

I have downloaded and opened a file attached to a spam email, is my computer infected?

If the opened file was an executable (.exe, .run, etc.) – most likely, yes – your device was infected. And if it was a document (.doc, .xls, .one, .pdf, etc.) – you might have avoided triggering an infection. These files may need additional user interaction (e.g., enabling macro commands, clicking on embedded content, etc.) to start downloading/installing malware.

Will Combo Cleaner remove malware infections present in email attachments?

Yes, Combo Cleaner can scan devices and eliminate practically all known malware infections. It must be emphasized that since high-end malicious software typically hides deep within the system – running a complete system scan is paramount.