Roundcube Mailbox Is Almost Full Scam: Fake Quota Alert
Written by: Lapain Epuran
Published on:
A mailbox notice claims you have used 1,993 MB of a 2,000 MB quota. The red storage bar is almost completely full, and the warning says new messages may stop arriving unless you clean the account now.
The numbers, table, and Roundcube name make the message look like a precise server alert. A button offers to open Roundcube and remove old mail.
The Roundcube Mailbox Is Almost Full scam is a phishing email. Its button does not manage storage. It leads to a copied login page built to capture the password for the recipient’s real mailbox.
Reconstructed example of the Roundcube Mailbox Is Almost Full phishing email. This illustration is not the original message.
Overview
The email reports a nearly exhausted 2,000 MB quota
The message presents itself as an automated Roundcube mailbox notification. It says the account has reached 1,993 MB, is over the 90% warning threshold, and may soon become unable to receive new messages.
A small table repeats the current usage, maximum quota, and threshold. The details are believable because storage warnings are a real part of many hosted email services.
The email also offers sensible-sounding advice about deleting unnecessary messages and emptying Trash and Junk. That harmless guidance prepares the recipient to trust the “Open Roundcube & Clean Up Mailbox” button.
Roundcube is real, but it did not send this message
Roundcube is a legitimate free and open-source webmail application used by hosting providers and organizations around the world. It is software installed and operated by individual mail administrators, not one global consumer email service.
Roundcube’s own support information explains that people with account or login problems should contact the hosting provider or IT team responsible for their mailbox. The software project does not independently manage every user’s storage quota.
Criminals copy the name and interface because many recipients recognize them from work or hosting accounts. That impersonation does not indicate a problem with the genuine Roundcube project.
The cleanup button opens a credential-stealing site
In the campaign analyzed, the button redirected to an unrelated domain displaying a fake Roundcube login screen. The recipient’s email address could be read from the phishing link and inserted into the username field.
The attackers want:
The full hosted-email address
The current mailbox password
Approval of any later multi-factor prompt
Access to messages, attachments, and address books
Password-reset links sent by connected services
A trusted account from which to contact customers or colleagues
Entering a password does not delete messages or increase storage. It sends the credential into a phishing workflow and may give the operator access to the real account.
Why the Storage Numbers Feel So Convincing
1,993 MB looks measured rather than invented
A rounded warning such as “your inbox is full” feels generic. A value only 7 MB below the limit looks as though it came directly from a server, even though anyone can type that number into an email template.
The scam does not prove the sender queried the mailbox. Identical figures can be shown to thousands of recipients regardless of their actual usage.
The message combines true advice with a false action
Deleting old messages and emptying Trash can genuinely free storage. The criminals use that fact to support a button that does something entirely different.
A real quota warning should be verified through the normal webmail portal or hosting control panel. Storage management does not require following an unfamiliar link from a surprise message.
A prefilled address creates false personalization
The fake login may already display the recipient’s email address. This is not evidence of a live connection to the mail server.
Phishing links often include an encoded address after a question mark or fragment. The webpage reads that text and places it into the form, creating the impression that the provider recognizes the user.
How the Roundcube Mailbox Is Almost Full Scam Works
Step 1: The campaign targets hosted and business email users
Attackers send storage notices to addresses found in public records, compromised lists, business directories, and earlier breaches. Domain-based mailboxes are useful targets because many are accessed through webmail.
The criminals do not need to know whether every recipient uses Roundcube. Sending at scale ensures that some messages reach people familiar with the name.
Step 2: The subject announces that mailbox storage is full
The subject is simple and practical, avoiding an obviously dramatic tone. People depend on email for work, bills, account alerts, and personal communication, so losing new messages feels immediately disruptive.
A recipient who has recently handled large attachments may find the claim especially plausible and open the email expecting a routine cleanup task.
The message lists 1,993 MB of 2,000 MB, a 90% threshold, and a nearly complete usage bar. Repetition gives the impression of an automated monitoring system.
None of those visual elements proves that the sender has access to the account. They are static content that can be reproduced in any HTML email.
Step 4: The cleanup button hides the real destination
The button label describes an expected action, but the underlying link leads away from the known mail portal. The observed phishing page used a domain unrelated to Roundcube or the recipient’s hosting provider.
Display text and destination are separate. A link can say “Open Roundcube” while pointing to any address chosen by the sender.
Step 5: A copied Roundcube screen requests the password
The landing page imitates the webmail login interface. It may include a familiar logo, color scheme, language, and a prefilled username to reduce hesitation.
The fake form is not connected to the user’s mailbox administration. Its purpose is to make handing over the password feel like a normal reauthentication step.
Step 6: Submitted credentials are collected
After the victim enters a password, the page sends it to an attacker-controlled endpoint. It may claim the password is wrong, display a loading screen, or redirect to a genuine website.
A redirect can hide the theft because the recipient eventually sees a familiar page and assumes the cleanup button malfunctioned.
Step 7: The password is tested against the real mail service
The criminals locate the actual webmail server using the address domain, public mail records, or common hosting paths. They then attempt to sign in with the captured credential.
If the same password is used elsewhere, automated credential-stuffing may target other services. Multi-factor approval requests can arrive as attackers try to complete access.
Step 8: The mailbox becomes a platform for further attacks
Intruders can read private correspondence, download attachments, reset connected accounts, and send phishing mail from a trusted address. They may also monitor new messages through forwarding or delegation.
For organizations, the account can support fake invoice changes, payroll redirection, or supplier impersonation. For individuals, it can expose shopping, cloud, and social accounts tied to email recovery.
How to Check a Real Roundcube Storage Warning
Open webmail through the address you normally use
Use a saved bookmark, your hosting control panel, or the URL supplied by your organization. Do not use the email button to establish the first connection.
Inspect storage information inside the signed-in account
Depending on the provider’s configuration, quota details may appear in webmail or the hosting dashboard. Compare those figures with the email rather than assuming the message has current data.
Ask the provider or administrator, not the Roundcube project
Roundcube is software deployed by other organizations. Questions about a mailbox quota belong with the company, school, web host, or IT department that operates the account.
Clean messages without authenticating through a notification
Once you are safely inside the real account, delete unwanted mail and empty the appropriate folders. If more storage is needed, review the hosting plan through the known customer portal.
Checks for Mail Administrators and Business Owners
Compare the claimed quota with server-side records
Administrators can confirm the account limit and current usage from the hosting panel or mail server. If dozens of users receive the same 1,993 MB warning despite different quotas, the campaign is immediately exposed.
Search for related messages across the organization
Use the sender, subject, link domain, message identifiers, and attachment hashes to locate other copies. Remove or quarantine them according to policy so additional users do not reach the phishing page.
Review authentication and forwarding changes
Look for unusual locations, new devices, repeated failures followed by success, newly created filters, external forwarding, and changes to recovery data. A password reset without session review can leave an active intruder unnoticed.
Make genuine quota notices easier to distinguish
Organizations can tell users where storage alerts appear, which sender address is used, and which portal handles cleanup. Customizing the webmail appearance and documenting the known domain reduces the persuasive power of generic Roundcube copies.
Short awareness reminders are most useful when they explain a specific action: never authenticate from a quota email, open the normal bookmark, and report any destination that differs.
Administrators should also preserve a copy of the original message with complete headers before removal. Header data can identify the sending infrastructure and authentication failures, while the linked address helps security teams block the active campaign across mail gateways and browsers.
Warning Signs in the Roundcube Mailbox Email
The sender domain does not match the organization hosting the mailbox.
The same 1,993 MB figure appears without evidence from the real account.
The message uses Roundcube as though it were the recipient’s direct provider.
The cleanup button leads to an unrelated external domain.
A new login is required before the user can see or delete any messages.
The username is prefilled from the link, creating artificial personalization.
The email predicts blocked delivery but offers no known support route.
Do not rely on the logo or storage bar. Verify the actual domain and enter the normal mail portal independently. A convincing screenshot-like layout can be copied without access to the server it claims to represent.
What to Do if You Have Fallen Victim to This Scam
Close the fake Roundcube page. Do not try another password or revisit it from the email. Save the original message if your administrator needs evidence.
Change the mailbox password through the legitimate host. Use the known webmail or control-panel address. If you do not know it, contact the organization responsible for the account through established details.
End unauthorized access. Sign out other sessions when the provider offers that option. Remove unknown delegates, connected apps, app passwords, forwarding addresses, and recovery changes.
Review mailbox activity. Check sent, deleted, archived, and trash folders. Examine filters and rules that might hide security warnings or forward copies of incoming mail.
Change reused passwords. Protect any service where the same credential appears, then enable multi-factor authentication. Reject unexpected prompts and never disclose a one-time code.
Tell IT, the web host, or the mail administrator. They can review server logs, reset sessions, block the phishing URL, and warn other users who received the same fake quota notice.
Scan any device that downloaded additional content. The observed campaign focuses on passwords, but related pages may deliver files. Malwarebytes can run a full scan for stealers, trojans, and unwanted software.
Use another protective layer for future browsing. AdGuard can block many reported phishing domains, malicious ads, and tracking calls. Continue checking destinations because new campaign domains may not yet be listed.
Warn contacts if the account sent unauthorized mail. Use another communication channel where possible. Monitor connected services and ignore recovery offers that request an advance payment.
Is Your Device Infected? Run a Free Malware Scan
Slow performance, constant pop-ups, or strange behavior? These are classic signs of a malware infection. The fastest way to find out is to scan your device with Malwarebytes Anti-Malware Free — one of the most trusted malware removal tools available.
The free version detects and removes the most common threats, including:
Adware — the cause of those annoying pop-ups
Browser hijackers — unwanted redirects and changed homepages
Trojans and spyware — hidden programs stealing your data
Potentially unwanted programs (PUPs) — software you never asked for
👉 Select your device below — Windows, Mac, or Android — then follow the simple steps to download Malwarebytes, scan your system, and remove any threats it finds. The whole process takes about 5 minutes.
Malwarebytes for WindowsMalwarebytes for MacMalwarebytes for Android
Run a Malware Scan with Malwarebytes for Windows
Malwarebytes is one of the most popular and trusted anti-malware tools for Windows — and it’s completely free for removing infections. It catches threats that many antivirus programs miss, including adware, browser hijackers, and trojans. Follow the steps below to scan and clean your PC in just a few minutes.
Download Malwarebytes
Click the button below to download the latest version of Malwarebytes for Windows from the official source. The free version is all you need — it will scan your computer and remove adware, browser hijackers, and other malicious software at no cost.
(The link opens in a new page where your download will start)
Install Malwarebytes
When the download finishes, open your Downloads folder and double-click the MBSetup file. If Windows shows a User Account Control pop-up, click “Yes” to allow the installation.
Follow the On-Screen Prompts to Install Malwarebytes
The setup wizard will walk you through a few quick screens:
Choose where you’re installing the program — “Personal Computer” or “Work Computer” — then click Next.
Malwarebytes will now install on your device. This usually takes under a minute.
When installation is complete, the “Welcome to Malwarebytes” screen will open automatically.
On the final screen, click Open Malwarebytes to launch the program.
Enable “Scan for Rootkits”
Before scanning, turn on rootkit detection so Malwarebytes can find even the most hidden threats. Click the Settings gear icon on the left side of the screen.
In the settings menu, find “Scan for rootkits” and click the toggle so it turns blue.
Done? Click “Dashboard” in the left pane to return to the main screen.
Start the Scan
Click the blue Scan button. Malwarebytes will automatically update its virus database and start checking your computer for malware.
Wait for the Scan to Finish
The scan checks your entire system for browser hijackers and other malicious programs, so it can take several minutes. Feel free to do something else — just check back occasionally to see the progress.
Quarantine the Detected Threats
When the scan is done, you’ll see a list of everything Malwarebytes found — malware, adware, and potentially unwanted programs. Click the “Quarantine” button to remove all of them at once.
Malwarebytes will now remove the malicious files and registry entries and move them safely into quarantine.
Restart Your Computer
Some threats can only be fully removed after a reboot. If Malwarebytes asks you to restart, click Yes. Once you’re logged back in, your PC is clean and you can continue with the next steps in this guide.
When the scan finishes, click Quarantine to remove everything Malwarebytes found. That’s it — your Windows PC is now clean of trojans, adware, and other malware, and should be back to running smoothly.
If your current antivirus allowed this malicious program on your computer, you may want to consider purchasing Malwarebytes Premium to protect against these types of threats in the future. If you are still having problems with your computer after completing these instructions, then please follow one of the steps:
Malwarebytes for Mac is a free on-demand scanner that removes the malware other security software tends to miss — adware, browser hijackers, and unwanted programs included. Cleaning an infected Mac with Malwarebytes has always been completely free, and it’s our go-to recommendation. Follow the steps below to scan and clean your Mac in just a few minutes.
Download Malwarebytes for Mac
Click the button below to download the latest version of Malwarebytes for Mac.
When the download finishes, open your Downloads folder and double-click the setup file to begin the installation.
Follow the On-Screen Prompts to Install Malwarebytes
The Malwarebytes for Mac Installer will guide you through a few quick screens. Click “Continue” and keep following the prompts until the installation completes.
When the installation is complete, Malwarebytes opens to the Welcome to Malwarebytes screen. Click “Get started“.
Select “Personal Computer” or “Work Computer”
Malwarebytes will ask what type of computer you’re installing it on. Click either Personal Computer or Work Computer, whichever applies.
Start the Scan
Click the “Scan” button. Malwarebytes will automatically update its detection database and begin checking your Mac for malware.
Wait for the Scan to Finish
Malwarebytes will scan your Mac for adware, browser hijackers, and other malicious programs. This can take a few minutes, so feel free to do something else — just check back occasionally to see the progress.
Quarantine the Detected Threats
When the scan is done, you’ll see a list of everything Malwarebytes found. Click the “Quarantine” button to remove all the threats at once.
Restart Your Mac
Malwarebytes will now remove all the malicious files it found. Some threats can only be fully removed after a reboot — if Malwarebytes asks you to restart, allow it. Once you’re logged back in, your Mac is clean.
Once the scan is done, remove every threat it detected. Your Mac is now free of adware, rogue browser extensions, and other potentially harmful software.
If your current antivirus allowed a malicious program on your computer, you might want to consider purchasing the full-featured version of Malwarebytes Anti-Malware to protect against these types of threats in the future. If you are still experiencing problems while trying to remove a malicious program from your computer, please ask for help in our Mac Malware Removal Help & Support forum.
Run a Malware Scan with Malwarebytes for Android
Malwarebytes for Android automatically detects and removes dangerous threats like malware and ransomware so you don’t have to worry about your most-used device being compromised. Aggressive detection of adware and potentially unwanted programs keeps your Android phone or tablet running smooth.
Download Malwarebytes for Android.
You can download Malwarebytes for Android by clicking the link below.
In the Google Play Store, tap “Install” to install Malwarebytes for Android on your device.
When the installation process has finished, tap “Open” to begin using Malwarebytes for Android. You can also open Malwarebytes by tapping on its icon in your phone menu or home screen.
Follow the on-screen prompts to complete the setup process
When Malwarebytes will open, you will see the Malwarebytes Setup Wizard which will guide you through a series of permissions and other setup options. This is the first of two screens that explain the difference between the Premium and Free versions. Swipe this screen to continue. Tap on “Got it” to proceed to the next step. Malwarebytes for Android will now ask for a set of permissions that are required to scan your device and protect it from malware. Tap on “Give permission” to continue. Tap on “Allow” to permit Malwarebytes to access the files on your phone.
Update database and run a scan with Malwarebytes for Android
You will now be prompted to update the Malwarebytes database and run a full system scan.
Click on “Update database” to update the Malwarebytes for Android definitions to the latest version, then click on “Run full scan” to perform a system scan.
Wait for the Malwarebytes scan to complete.
Malwarebytes will now start scanning your phone for adware and other malicious apps. This process can take a few minutes, so we suggest you do something else and periodically check on the status of the scan to see when it is finished.
Click on “Remove Selected”.
When the scan has been completed, you will be presented with a screen showing the malware infections that Malwarebytes for Android has detected. To remove the malicious apps that Malwarebytes has found, tap on the “Remove Selected” button.
Restart your phone.
Malwarebytes for Android will now remove all the malicious apps that it has found. To complete the malware removal process, Malwarebytes may ask you to restart your device.
After the scan, tap Remove Selected to delete all detected threats. Your Android phone is now clean — no more malicious apps, adware, or browser redirects.
If your current antivirus allowed a malicious app on your phone, you may want to consider purchasing the full-featured version of Malwarebytes to protect against these types of threats in the future. If you are still having problems with your phone after completing these instructions, then please follow one of the steps:
Restore your phone to factory settings by going to Settings > General management > Reset > Factory data reset.
Now that your device is clean, keep it that way. Most infections start with a malicious ad or a fake download button — so blocking them at the source is your best defense.
We recommend AdGuard, which blocks malicious ads, phishing pages, and dangerous redirects before they can reach you.
Is the Roundcube Mailbox Is Almost Full email genuine?
No. The campaign uses invented quota data and an external login page to collect credentials. Check storage inside the normal webmail account instead.
Does Roundcube send storage warnings directly to all users?
Roundcube is software operated by individual providers and organizations. Your mail host or administrator controls account notices, limits, and support.
What if my mailbox really is nearly full?
Open the known webmail portal independently and inspect the quota there. Delete messages or change the plan only through the legitimate account dashboard.
Why was my email address already in the fake form?
The phishing link can carry the address as a parameter. The page simply copies it into the field, which does not prove access to the real mailbox.
Is clicking the button enough to compromise the account?
The primary theft occurs when credentials are submitted. If you only opened the page, close it and scan the device if anything downloaded or installed.
Can the attacker remain after I change the password?
Potentially, if a session, delegate, app password, or forwarding rule remains active. Review those settings and ask the provider to revoke all sessions if needed.
The Bottom Line
The Roundcube Mailbox Is Almost Full scam makes invented storage figures look like live server data. Its cleanup button leads to a copied login page, not a mailbox-management screen.
Roundcube is legitimate software, but the provider or IT team operating your account controls its quota. Visit that service directly, and if a password was submitted to the fake page, change it and inspect every access and forwarding setting without delay.
10 Rules to Avoid Online Scams
Here are 10 practical safety rules to help you avoid malware, online shopping scams, crypto scams, and other online fraud. Each tip includes a quick “if you already got hit” action.
Stop and verify before you click, log in, download, or pay.
Most scams win by creating urgency. Verify using a trusted method: type the website address yourself, use the official app, or call a known number (not the one in the message).
If you already clicked: close the page, do not enter passwords, and run a malware scan.
Keep your operating system, browser, and apps updated.
Updates patch security holes used by malware and malicious ads. Turn on automatic updates where possible.
If you saw a scary “update now” pop-up: close it and update only through your device settings or the official app store.
Use layered protection: antivirus plus an ad blocker.
Antivirus helps block malware. An ad blocker reduces scam redirects, phishing pages, and malvertising.
If your browser is acting weird: remove unknown extensions, reset the browser, then run a full scan.
Install apps, software, and extensions only from official sources.
Avoid cracked software, “keygens,” and random downloads. During installs, choose Custom/Advanced and decline bundled offers you do not recognize.
If you already installed something suspicious: uninstall it, restart, and scan again.
Treat links and attachments as untrusted by default.
Phishing often impersonates delivery services, banks, and popular brands. If it is unexpected, do not open attachments or log in through the message.
If you entered credentials: change the password immediately and enable 2FA.
Shop safely: research the store, then pay with protection.
Be cautious with brand-new stores, “closing sale” stories, and prices that make no sense. Prefer credit cards or PayPal for dispute options. Avoid wire transfers, gift cards, and crypto payments.
If you already paid: contact your card issuer or PayPal quickly to dispute the transaction.
Crypto rule: never pay a “fee” to withdraw or recover money.
Common patterns include fake profits, then “tax,” “gas,” or “verification” fees. Another is a “recovery agent” who demands upfront crypto.
If you already sent crypto: stop paying, save evidence (wallet addresses, TXIDs, chats), and report the scam to the platform used.
Secure your accounts with unique passwords and 2FA (start with email).
Use a password manager and unique passwords for every account. Enable 2FA using an authenticator app when possible.
If you suspect an account takeover: change passwords, sign out of all devices, and review recent logins and recovery settings.
Back up important files and keep one backup offline.
Backups protect you from ransomware and device failure. Keep at least one backup on an external drive that is not always connected.
If you suspect infection: do not connect backup drives until the system is clean.
If you think you are a victim: stop losses, document evidence, and escalate fast.
Move quickly. Speed matters for disputes, account recovery, and limiting damage.
Stop payments and contact: do not send more money or respond to the scammer.
Call your bank or card issuer: block transactions, replace the card if needed, and start a dispute or chargeback.
Secure your email first: change the email password, enable 2FA, and remove unfamiliar recovery options.
Secure other accounts: change passwords, enable 2FA, and log out of all sessions.
Scan your device: remove suspicious apps or extensions, then run a full malware scan.
Save evidence: screenshots, emails, order pages, tracking pages, wallet addresses, TXIDs, and chat logs.
Report it: to the payment provider, marketplace, social platform, exchange, or wallet service involved.
These rules are intentionally simple. Most online losses happen when decisions are rushed. Slow down, verify independently, and use payment methods and account controls that give you recourse.
Hello! I'm Lapain Epuran, your go-to source for detailed and honest product reviews. From tech gadgets to miracle cures, I provide insights to help you make informed choices. Join me as we discover what's truly worth your time and money.
