The company claims that the e-mails are being hijacked and manipulated by Yahoo, which provides an unfair advantage for other competitors, according to press reports.
The focus of the lawsuit is an ad format that provides pop ups that open when a reader scrolls over certain text.
According to the company, these pop ups advertise unauthorized sellers and competitors, and Mary Kay is alleging the practice could be confusing for consumers and constitutes trademark infringement.
In the lawsuit filed in a federal district court in Dallas, Texas, earlier this week, Mary Kay called for Yahoo to stop the practice and pay monetary damages.
“We want Yahoo to stop what its doing. Yahoo mail needs to stop infringing on our tradename,” said Mary Kay spokesperson Crayton Webb, as quoted in media news service MediaPost.
Taking issue with pop ups
Mary Kay operates through a network of independent beauty consultants that directly sell to consumers.
It takes issue with the pop up adverts in the e mails as they advertise unauthorised sellers – vendors that do not belong to the network of beauty consultants.
However, it is unclear whether the court will agree these vendors are truly unauthorized.
Neither Mary Kay nor Yahoo was available for comment at the time of going to press.