In a forum on social networking site Reddit, Game of Thrones viewers reported receiving emails concerning the downloading of leaked episodes.
One Reddit user posted the full email he had received from Bell Canada, whose online television packages include the HBO Canada channel. The email stated that Bell Canada had received notification that a leaked Game of Thrones episode had been illegally downloaded from the user's IP address.
"The title in question is: Game of Thrones. As the owner of and/or subscriber using the IP address, HBO requests that you immediately take steps to prevent further downloading or uploading of HBO content without authorization," Bell Canada stated in the email.
Bell Canada added that no one was authorized to "exhibit, reproduce, transmit or otherwise distribute HBO Properties" without written consent.
The Reddit user believed that Bell Canada had been contacted by HBO's anti-piracy partner, IP-Echelon. When contacted by CNBC, IP-Echelon declined to comment.
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Jeff Cusson, senior vice president of corporate communications at HBO, told CNBC that the type of emails described by Reddit users were nothing "new" and weren't specific to the four leaked episodes.
"This action is not specific to the four episodes, nor is it new. Notifications to Internet service providers that their users are illegally downloading is standard operating procedure in our digital anti-piracy efforts," Cusson told CNBC on Monday.