INDIAN WELLS, Calif. — Explaining on Monday how she tested positive for the recently banned substance meldonium, Maria Sharapova admitted that she received an email from the World Anti-Doping Agency in December that contained changes in its prohibited list. The list included meldonium.

“I did not look at that list,” said Sharapova, who has been taking the substance since 2006.

The former WADA president Richard W. Pound called out her “willful negligence,” saying to BBC Sport that she was “reckless beyond description” for failing to heed the prohibition.

But Sharapova is not the only player paying little mind to messages from the antidoping agency. Many players and coaches at the BNP Paribas Open here this week conceded that they, too, do not thoroughly read emails from WADA.

“No one clicks that link,” said Jiri Fencl, a Czech coach.

Some dismissed the messages as irrelevant to their own regimens or too complicated to be useful; others said that they trusted someone in their inner circle would be keeping tabs on their behalf.