BOSTON, Oct 8 (Reuters) - Two former eBay Inc workers pleaded guilty on Thursday to participating in an extensive cyberstalking campaign against a Massachusetts couple whose online newsletter was viewed by top executives as critical of the e-commerce company.

Federal prosecutors in Boston said former eBay global intelligence team members Stephanie Popp and Veronica Zea along with other employees harassed the couple through Twitter and sent them disturbing packages like a bloody Halloween pig mask.

Popp, eBay's former senior manager of global intelligence, and Zea, a contractor who worked as an intelligence analyst, pleaded guilty to conspiring to commit cyberstalking and conspiring to tamper with a witness.

Prosecutors plan to recommend prison terms of 41 months for Popp, 33, and 30 months for Zea, 26, when they are later sentenced.

They are among seven defendants, including onetime eBay security executives James Baugh and David Harville, who prosecutors said targeted the couple in Natick, Massachusetts, with threatening messages and unwanted deliveries, including a box of live cockroaches and a funeral wreath.

Prosecutors said they also sent pornography in the couple's name to neighbors and conducted covert surveillance, in a bid to terrorize the couple and deter them from criticizing eBay.

They did so after two top executives expressed frustration with the newsletter, EcommerceBytes. The executives included former Chief Executive Devin Wenig, who a person familiar with the matter has said is the "Executive 1" identified in court papers.

Prosecutors said Wenig texted the other executive after the newsletter's editor published an article about eBay, saying it was time to "take her down."

Wenig has not been charged and has denied knowing about the scheme. He is a member of General Motors Co's board. Wenig's spokesman did not respond to a request for comment.

Three other former eBay employees are scheduled to plead guilty later this month. (Reporting by Nate Raymond in Boston Editing by Matthew Lewis)