https://www.cnet.com/news/twitter-apologizes-for-not-addressing-threat-later-linked-to-mail-bombs/

"We made a mistake when Rochelle Ritchie first alerted us to the threat made against her," Twitter tweeted from its Twitter Safety account. "The Tweet clearly violated our rules and should have been removed. We are deeply sorry for that error."

"We want Twitter to be a place where people feel safe," the company continued, "and we know we have lot of work to do."