An urgent warning has been issued to the British public after the emergence of millions of scam messages.
Consumer group Which? has warned that people should keep an eye out for "extremely convincing" scam texts that could steal your bank information and personal data.
Variations of the same text have been circulating informing victims that a parcel has failed to be delivered and asking them to click a link to book or reschedule a delivery, as the Liverpool Echo reports.
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These links can send victims to very convincing fake websites where they're asked to fill in their personal details on a form, putting them at risk of identity fraud.
Victims may also be asked to pay a charge for re-delivery, then be told the request has been "processed successfully".
One way to identify a scam is to simply remember that the Post Office never sends out texts or emails regarding a parcel.
Adam French, Which? consumer rights editor, said: "If people input their details and pay for a new delivery date, the scammers redirect them to the official Post Office website - making this fake even more plausible.
"Consumers should be on high alert for scams and, if in any doubt, should verify the text directly with the company before giving any personal information.
"If you've entered any bank details, contact your bank immediately to ensure the scammer cannot take any more money from your account and ask to be reimbursed. You can also report any attempted scam to Action Fraud."
A Post Office spokesperson said: "People are being tricked by fake texts claiming to be from Post Office, but Post Office will never send texts about parcels or mail.
"This is because Post Office does not deliver parcels or letters. We're grateful to Which? for alerting us to this fake website which we were already aware of and had taken action to get it blocked.
"Cyber criminals are frequently trying to get people to click on links in texts regarding undelivered shipping fees and undelivered items and directing them to fake websites purporting to be an official Post Office website.
"We are working hard to raise awareness about these fake texts in our name to help stop people being conned.
"As soon as we are aware that a fake Post Office web page is up and running we take immediate action to have the site taken down.
"This week we have launched a social media campaign aimed at those aged 50-plus to warn them of scams that may use the Post Office name and what to do if they have any suspicions."
If you've been targeted by a scam text, you can forward it to the network provider on 7726 - Which? also recommends alerting the company being imitated.
The Post Office spokesperson added: "Post Office use digital monitoring systems that alert us to any website set up with our name in the URL.
"Once we are alerted (within hours to 24 hours of a URL being registered) we monitor the URL for any web page that is set up, specifically using our brand.
"We are only able to take action once a website is set up and displays our branding and trademark.
"We submit a request for 'takedown' with the domain registrar that the URL is registered with. In a lot of these cases, these websites are only live for a matter of hours - mainly because people have already reported the URL.
"We take enforcement action and apply to the domain (URL) registrar for unauthorised use of our brand, and once the registrar accepts our claim they will disconnect the URL from the website's hosting service, rendering the site 'offline'.
