Facebook has changed some of its user rules to curtail online harassment and domestic violence.

The social network said in a post Tuesday that users can now choose to read or ignore abusive or threatening messages and posts without the sender knowing they are doing so.

"If someone is being harassed, blocking the abuser sometimes prompts additional harassment, particularly offline," Facebook said in a post written by Antigone Davis, the company's head of global safety. "We've also heard from groups that work with survivors of domestic violence that being able to see messages is often a valuable tool to assess if there is risk of additional abuse," Davis wrote.

The product changes are part of broader efforts to combat online violence that include using artificial intelligence to prevent abusive users from opening duplicate or fake accounts.

"These automated features help us identify fake accounts more quickly and block millions of them at registration every day," the post said.

Still, the company's software can't catch all abuse among its more than 2 billion global users.

"Sometimes a new account created by someone who was previously blocked might not get caught by these features," according to Facebook.

The messaging changes are meant to help protect users from those who slip through and create new accounts to continue the harassment or abuse.

Facebook's head of security, Alex Stamos, said in August that the company was then blocking more than a million attempts a day by users trying to create fake or duplicate accounts.