Richard Sackler has stated that he was not involved in the company’s marketing activities. However, the 2008 email appears to be among the first internal company emails to suggest that Mr. Sackler urged the promotion of higher strengths of OxyContin. Two other members of the family, Jonathan and Mortimer Sackler, were copied in on the email, according to the new disclosures.

That email is one of several disclosures that emerged Thursday when Ms. Healey filed a version of her lawsuit that contained information that Purdue Pharma had sought to block from public view.

In a filing last week, several parts of the lawsuit were redacted, but a Massachusetts state judge agreed with several groups, including The New York Times and other media organizations, that the entire complaint should be made public. A last-minute effort Thursday by Purdue Pharma to block the release failed.

The drug maker has long sought to depict the Sackler family as removed from the company’s day-to-day operations. The Sacklers are one of the richest families in the United States, with much of their wealth derived from sales of OxyContin. Their name graces museums and medical schools around the world, and the new revelations are likely to renew calls for institutions to decline their philanthropic gifts.

In a statement, Purdue Pharma, which is based in Stamford, Conn., said that Thursday’s release of the remaining portions of the Massachusetts lawsuit was “part of a continuing effort to single out Purdue, blame it for the entire opioid crisis, and try the case in the court of public opinion rather than the justice system.”