Microsoft employees have discovered that any emails they send with the terms “Palestine” or “Gaza” are getting temporarily blocked from being sent to recipients inside and outside the company. The No Azure for Apartheid (NOAA) protest group reports that “dozens of Microsoft workers” have been unable to send emails with the words “‘Palestine,” “Gaza,” and “Genocide” in email subject lines or in the body of a message.

“Words like ‘Israel’ or ‘P4lestine’ do not trigger such a block,” say NOAA organizers. “NOAA believes this is an attempt by Microsoft to silence worker free speech and is a censorship enacted by Microsoft leadership to discriminate against Palestinian workers and their allies.“

Microsoft confirmed to The Verge that it has implemented some form of email changes to reduce “politically focused emails” inside the company.

“Emailing large numbers of employees about any topic not related to work is not appropriate. We have an established forum for employees who have opted in to political issues,” says Microsoft spokesperson Frank Shaw in a statement to The Verge. “Over the past couple of days, a number of politically focused emails have been sent to tens of thousands of employees across the company and we have taken measures to try and reduce those emails to those that have not opted in.”

The block of these terms comes in a week when current and former Microsoft employees have been protesting against the company’s contracts with the Israeli government during Microsoft’s Build developer conference. A Microsoft employee, Joe Lopez, disrupted the opening keynote of Build on Monday. During CEO Satya Nadella’s keynote Lopez yelled, “How about you show Israeli war crimes are powered by Azure?” Lopez then sent an email to thousands of Microsoft employees, and the company fired him on Monday.

This week’s protests come just days after Microsoft acknowledged its cloud and AI contracts with Israel, but claimed that an internal and external review had found “no evidence” that its tools were used to “target or harm people” in Gaza.