Vodafone customers are being warned to watch out for a number of viral messages that could leave you out of pocket.
Dozens of customers have reported look-alike emails that are landing in their inboxes, claiming to be from the telecoms giant.
The emails claim that their bills are 'ready to view' - with charges as high as £400 - sending customers into a panic.
However, in reality, they're 'phishing' emails - messages that are designed to manipulate the recipient into handing over sensitive information, such as bank account numbers, passwords and addresses, through fraudulent links.
UK fraud agency, Get Safe Online, first issued the alert on Twitter - and dozens of people have since come forward to shame the attackers.
The emails - which may appear convincing at first glance - read: "You can now take a look and manage your latest Vodafone bill for invoice date 02/08/2017. Your total bill for this month is 441.46."
However, upon closer inspection, there are a number of tell-tale signs that suggest it is in fact fake.
Firstly, the email address is clearly not from Vodafone - the mailer appears to be from '@mail2marketing.com - although different messages will show different addresses.
The emails also open the line with 'dear customer' - official emails from registered firms will always address you by your full name.
The links in the emails are likely to contain Emotet - a type of malware that could steal personal details by installing software into your browser.
In other cases, they may direct you to a cloned version of the Vodafone website - a common tactic used by online hackers, especially in the case of Amazon scams .
Vodafone is not the first firm to be targeted by fraudsters. PayPal, HMRC and even local councils have been caught out by criminals in recent months.
Last month, the City of London's anti-fraud body Action Fraud issued a warning over fake PayPal emails .
It said a number of customers had come forward to report suspicious messages citing 'unusual activity' on their accounts.
The emails contained links to cloned versions of the PayPal website.
Deputy Head of Action Fraud, Steve Proffitt said: "Fraudsters are increasingly targeting people with very professional looking emails warning that online accounts have been compromised and asking you to click on links to verify your details.
"If you have received one of these fake emails, we are advising people not to follow the links in the email as by logging into your account, you are providing fraudsters with your login details which gives them access to your account.
"Always contact the fraud department of the organisation directly from the contact details you have on your statements or bank card and explain the contents of the email you have received."
Take Five's top tips to help spot a scam email
If you receive an email that claims to be 'official' think twice before opening it and never click on any links provided.
If you spot any of these signs, report and bin the message. Here are warning signs to watch for:
The sender's address doesn't match the website address of the organisation it says it's from. Roll your mouse pointer over the sender's name to reveal its true address.
The email doesn't use your correct name – instead using something like "Dear customer".
There's a sense of urgency, asking you to act immediately.
There's a prominent website link which may seem like the proper address, but with one character different.
There's a request for personal information.
There are spelling and grammatical errors.
What to do if you think you've been scammed
If you receive an email or call that you don't recognise, think twice before replying or opening any attachments.
Change your passwords and report your concerns to Action Fraud - they'll be able to look into the case for you.
Where you believe your bank details may have been compromised, notify your bank as soon as possible.
To find out more about fraud, the risks and how to stay safe, see our guide on how to stay safe here.