NEW YORK HBO, which acknowledged Monday that hackers had broken into its systems and stolen "proprietary information," now says it's unlikely they breached the network's entire email system.

In an email to employees, CEO Richard Plepler wrote that "we do not believe that our email system as a whole has been compromised." He added that a review continues, and said HBO is hiring an outside firm to help employees monitor their financial accounts.

Purported hackers said in email that they'd accessed HBO's internal network and email system and then posted stolen information online. An archived version of the website they named appeared to have links to downloadable episodes for several HBO shows, including "Insecure" and "Ballers," and what it said was a link to "script & film" to two "Game of Thrones" episodes, including one that is upcoming. They also stole episodes of "Curb Your Enthusiasm," Bloomberg reported.

The site was not loading Thursday afternoon. But HBO appeared to indirectly confirm that this website linked to potentially sensitive internal material including "documents, images, videos and sound."

Hackers also posted user names and passwords of a senior executive, Variety reported, at least one of which could have given access to the executive's work email.

On Tuesday, a company called IP-Echelon filed a report with Google on behalf of HBO, noting that the named website "shares thousands of Home Box Office (HBO) internal company documents." IP-Echelon Pty Ltd. regularly files such copyright-infringement notices on behalf of large media entertainment companies, including HBO.

Federal law requires internet companies like Google to remove links to sites that infringe copyright once they receive such notifications. Google routinely forwards such notices to the longstanding public-interest repository Lumen, formerly known as Chilling Effects, once it has complied.

A Google spokeswoman did not respond to requests for comment. An HBO spokesman declined to comment on the takedown notice. Messages left with IP-Echelon were not answered.

Previous hacks have created significant repercussions in Hollywood. Sony struggled in the aftermath of its huge hack in 2014, which leaked embarrassing employee emails as well as films and revealed, among other things, a persistent gender pay gap at the company.

But earlier this year, when another hacker held stolen episodes of new Netflix shows for ransom, Netflix apparently refused to pay. When the episodes appeared online, the company merely shrugged.