HBO is targeting viewers outside of the U.S. who are subscribing to HBO Now using virtual private networks, threatening to deactivate their accounts if they continue to access the U.S.-only streaming service.

The U.S.-based television company has been sending emails to people who have subscribed to the service in Canada and overseas.

One email, obtained by Torrent Freak, says that all access to HBO Now outside of the United States "is prohibited by our terms of use," and that continued use of the service will result in their terminating the service "without further notice."

HBO Now, which launched earlier this month, is a video-on-demand service that doesn't require a subscription to the network's traditional television service. The main draw is for HBO's original series, including Silicon Valley and Game of Thrones, for $14.99 US — a fraction of the cost of a regular TV subscription.

Access with VPN

People outside the U.S. can't legally access HBO Now, so many have taken to using virtual private network (VPN) services to get their fix of political intrigue and bloodshed in Westeros without having to subscribe to more expansive (and expensive) services to do so.

HBO CEO Richard Plepler talks about HBO Now for Apple TV during an Apple event in San Francisco on March 9. (Eric Risberg/AP) VPN services mask your IP address, hiding your location and granting abilities such as accessing content that are geofenced, such as HBO Now and other television streaming services like Hulu, which aren't available in Canada.

HBO Canada is available as a package that includes other channels like The Movie Network from providers like Bell and Rogers, and costs $20 on top of base TV subscription packages, which start from around $40 and can climb to more than $100 a month.

Older HBO programming is available on CraveTV, Bell's streaming service, but you can only pay for it if you're already a Bell TV subscriber. In other words, if you're looking for a low-cost equivalent to HBO Now in Canada without being tethered to the television set, you're out of luck.

No stand-alone HBO in Canada

Technology reporter Peter Nowak doesn't think Thrones fans will be able to legally watch their favourite HBO shows without a TV subscription any time soon. "Bell is basically driving a truck full of cash into HBO's headquarters," he says, to keep HBO from choosing to offer its services outside of the traditional TV model.

HBO might conclude that it'll make more money offering HBO Now as a stand-alone service in Canada like it does in the U.S., if recent figures are any indication. About 95,000 fewer household in Canada had a cable TV or satellite subscription in 2014, and experts estimate that number will grow as more people gravitate toward the on-demand or streaming services like HBO Now or Netflix.

But until such a shift happens, Canadians will either have to bite down and pay for the full TV suite to access their one or two favourite shows, or download them via VPN or BitTorrent and risk getting hit with cease and desists from their ISPs.

Game of Thrones pirated by millions

The crackdown is coming as the latest season of Game of Thrones continues its reign as the most-pirated show online. TorrentFreak reported that over 32 million people paid the iron price in April, after the first four episodes of season 5 leaked online before its April 12 premiere.

Season 5's first episode alone was downloaded more than 13 million times, with 1.3 million of those coming from Canadian IP addresses.

Last week, a user on Reddit posted a cease and desist email he received from Bell, his internet service provider. The Redditor, MrSourz, said "someone in [his] apartment downloaded" the first episode of Games of Thrones' fifth season.

"HBO requests that you immediately take steps to prevent further downloading or uploading of HBO content without authorization," the email reads.

HBO also ordered a Brooklyn bar to terminate its Game of Thrones screenings, and sent takedown notices to dozens of users who live streamed the season 5 premiere with Periscope, Twitter's new streaming mobile app.