Do not trust fake "Your Messages Couldn't Be Delivered" emails

What kind of email is "Your Messages Couldn't Be Delivered"?

After inspecting the "Your Messages Couldn't Be Delivered" email, we determined that it is spam. By claiming that outgoing messages failed delivery, the letter aims to trick the recipient into providing their email account log-in credentials to a phishing website.

"Your Messages Couldn't Be Delivered" email scam overview

The email with the subject "Important: The mailbox password for [recipient's_email_address] has expired" (may vary) informs that the recipient's messages failed delivery. This supposed issue occurred because the email account has not been updated.

It must be stressed that the claims made by the "Your Messages Couldn't Be Delivered" email are false, and this mail is not associated with any genuine service providers.

After the "Click Here to Retrieve and Initiate Delivery" link is clicked, the user is redirected to a phishing website presented as an email account sign-in page. By attempting to log in through this site – the user will expose their email.

In addition to stealing the compromised account, the cyber criminals may also gain access to the content registered through it.

To expand upon the potential misuse, scammers can steal the identities of social account owners (e.g., emails, social networking, social media, etc.) and ask the contacts/friends/followers for loans or donations, promote scams, and spread malware by sharing malicious files/links.

Hijacked finance-related accounts (e.g., online banking, money transferring, e-commerce, digital wallets, etc.) can be used to make fraudulent transactions and/or online purchases.

To summarize, victims of spam mail like "Your Messages Couldn't Be Delivered" can experience serious privacy issues, financial losses, and even identity theft.

If you have entered your log-in credentials into a phishing webpage – immediately change the passwords of all possibly exposed accounts and inform their official support.

Threat Summary:

Name	"Your Messages Couldn't Be Delivered" phishing email
Threat Type	Phishing, Scam, Social Engineering, Fraud
Fake Claim	Outgoing emails failed delivery because the recipient's account has not been updated.
Symptoms	Unauthorized online purchases, changed online account passwords, identity theft, illegal access of the computer.
Distribution methods	Deceptive emails, rogue online pop-up ads, search engine poisoning techniques, misspelled domains.
Damage	Loss of sensitive private information, monetary loss, identity theft.
Malware Removal (Windows)	To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. ▼ Download Combo Cleaner 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 read more.

Phishing spam campaign examples

"Routine System Maintenance", "Process Of Enhancing Our Webmail Software", "Chan & Zuckerberg Initiative (CZI)", and "Account And Service(s) Scheduled For Deletion" are merely a few examples of phishing emails that we have reviewed recently.

Spam mail is used to facilitate a wide variety of scams and even to proliferate malware. These emails can be variously disguised, including as messages from legitimate companies, organizations, service providers, authorities, and other entities.

How do spam campaigns infect computers?

Cyber criminals commonly use spam campaigns to distribute malware. This method involves malicious files that are either attached to or linked inside the emails. These files can be in various formats, e.g., documents (Microsoft Office, Microsoft OneNote, PDF, etc.), archives (RAR, ZIP, etc.), executables (.exe, .run, etc.), JavaScript, and so forth.

Upon opening, infectious files jumpstart system infection processes. However, some formats may need extra actions to trigger malware download/installation. To elaborate, Microsoft Office documents require users to enable macro commands (i.e., editing/content), while OneNote files need them to click on embedded links/files.

How to avoid installation of malware?

It is paramount to treat incoming emails and other messages with care. Attachments or links present in suspect mail must not be opened, as they can be malicious. We recommend using Microsoft Office versions released after 2010 since they have the "Protected View" mode that prevents automatic macro command execution.

However, malware is not spread exclusively through spam mail. Therefore, we advise being vigilant when browsing since fake and dangerous online content usually appears legitimate and harmless.

Another recommendation is to download only from official and trustworthy sources. Additionally, all programs must be activated and updated using genuine functions/tools, as illegal activation tools ("cracks") and third-party updaters can contain malware.

We must emphasize the importance of having a reputable anti-virus installed and kept up-to-date. Security software must be used to perform regular system scans and to remove detected threats. 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 "Your Messages Couldn't Be Delivered" spam email letter:

Subject: Important: The mailbox password for - has expired

Your messages couldn't be delivered
Your recent outgoing messages couldn't be delivered due to lack of updating your email account.

Further information: Connection timed out
To auto initiate delivery:  (Click Here to Retrieve and Initiate Delivery)

Delivery report for: -

Screenshot of the phishing website promoted by the "Your Messages Couldn't Be Delivered" spam campaign:

Another example of an email from "Your Messages Couldn't Be Delivered" spam campaign:

Text presented within:

Subject: Undeliverable: (9) Mails Returned to Sender

I'm sorry to have to inform you that 9 of your messages could not be delivered to one or more recipients.

For further assistance, please verify messages to - postmaster with below link.

Verify Delivery Error

Your account will be blocked from sending messages on failure to carry out this above activity.

Screenshot of the promoted phishing site:

Another example of unsuccessful message delivery-themed spam email promoting a phishing site:

Text presented within:

Subject: Unsuccessful Mail Delivery Report

This is the mail system at host us3.outbound.********.

Your outgoing  message was unsuccessfully delivered to the destination(s) listed due to low bandwidth space.
Go to Email account settings below to review undelivered mails and fix bugs.

Email Account Settings
********
Copyright © 2023 All Rights Reserved.

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Quick menu:

• What is "Your Messages Couldn't Be Delivered" phishing email?
• Types of malicious emails.
• How to spot a malicious email?
• What to do if you fell for an email scam?

Types of malicious emails:

Phishing Emails

Most commonly, cybercriminals use deceptive emails to trick Internet users into giving away their sensitive private information, for example, login information for various online services, email accounts, or online banking information.

Such attacks are called phishing. In a phishing attack, cybercriminals usually send an email message with some popular service logo (for example, Microsoft, DHL, Amazon, Netflix), create urgency (wrong shipping address, expired password, etc.), and place a link which they hope their potential victims will click on.

After clicking the link presented in such email message, victims are redirected to a fake website that looks identical or extremely similar to the original one. Victims are then asked to enter their password, credit card details, or some other information that gets stolen by cybercriminals.

Emails with Malicious Attachments

Another popular attack vector is email spam with malicious attachments that infect users' computers with malware. Malicious attachments usually carry trojans that are capable of stealing passwords, banking information, and other sensitive information.

In such attacks, cybercriminals' main goal is to trick their potential victims into opening an infected email attachment. To achieve this goal, email messages usually talk about recently received invoices, faxes, or voice messages.

If a potential victim falls for the lure and opens the attachment, their computers get infected, and cybercriminals can collect a lot of sensitive information.

While it's a more complicated method to steal personal information (spam filters and antivirus programs usually detect such attempts), if successful, cybercriminals can get a much wider array of data and can collect information for a long period of time.

Sextortion Emails

This is a type of phishing. In this case, users receive an email claiming that a cybercriminal could access the webcam of the potential victim and has a video recording of one's masturbation.

To get rid of the video, victims are asked to pay a ransom (usually using Bitcoin or another cryptocurrency). Nevertheless, all of these claims are false - users who receive such emails should ignore and delete them.

How to spot a malicious email?

While cyber criminals try to make their lure emails look trustworthy, here are some things that you should look for when trying to spot a phishing email:

• Check the sender's ("from") email address: Hover your mouse over the "from" address and check if it's legitimate. For example, if you received an email from Microsoft, be sure to check if the email address is @microsoft.com and not something suspicious like @m1crosoft.com, @microsfot.com, @account-security-noreply.com, etc.
• Check for generic greetings: If the greeting in the email is "Dear user", "Dear @youremail.com", "Dear valued customer", this should raise suspiciousness. Most commonly, companies call you by your name. Lack of this information could signal a phishing attempt.
• Check the links in the email: Hover your mouse over the link presented in the email, if the link that appears seems suspicious, don't click it. For example, if you received an email from Microsoft and the link in the email shows that it will go to firebasestorage.googleapis.com/v0... you shouldn't trust it. It's best not to click any links in the emails but to visit the company website that sent you the email in the first place.
• Don't blindly trust email attachments: Most commonly, legitimate companies will ask you to log in to their website and to view any documents there; if you received an email with an attachment, it's a good idea to scan it with an antivirus application. Infected email attachments are a common attack vector used by cybercriminals.

To minimise the risk of opening phishing and malicious emails we recommend using Combo Cleaner Antivirus for Windows. 

Example of a spam email:

What to do if you fell for an email scam?

• If you clicked on a link in a phishing email and entered your password - be sure to change your password as soon as possible. Usually, cybercriminals collect stolen credentials and then sell them to other groups that use them for malicious purposes. If you change your password in a timely manner, there's a chance that criminals won't have enough time to do any damage.
• If you entered your credit card information - contact your bank as soon as possible and explain the situation. There's a good chance that you will need to cancel your compromised credit card and get a new one.
• If you see any signs of identity theft - you should immediately contact the Federal Trade Commission. This institution will collect information about your situation and create a personal recovery plan.
• If you opened a malicious attachment - your computer is probably infected, you should scan it with a reputable antivirus application. For this purpose, we recommend using Combo Cleaner Antivirus for Windows.
• Help other Internet users - report phishing emails to Anti-Phishing Working Group, FBI’s Internet Crime Complaint Center, National Fraud Information Center and U.S. Department of Justice.

Frequently Asked Questions (FAQ)

Why did I receive this email?

Spam emails are not personal. They are sent out in mass-scale campaigns – hence, 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 provided your log-in credentials – change the passwords of all possibly exposed accounts and inform their official support without delay. If you have disclosed other private information (e.g., ID card details, credit card numbers, etc.) – immediately contact the appropriate authorities.

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

Merely opening/reading an email will not trigger any malware download/installation processes. Devices are infected when malicious attachments or links are opened/clicked.

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. However, you might have avoided this if it was a document (.doc, .xls, .one, .pdf, etc.). These formats may need additional actions (e.g., enabling macros, clicking embedded content, etc.) to initiate malware download/installation chains.

Will Combo Cleaner remove malware infections present in email attachments?

Yes, Combo Cleaner is capable of detecting and eliminating most of the known malware infections. Note that performing a complete system scan is paramount since sophisticated malicious programs typically hide deep within systems.

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