It took a week and an organized campaign, but negative reaction to a letter sent by tech executives in support of the proposed Cybersecurity Information Sharing Act (CISA) has built on social media. In the first day of the campaign, 15,000 emails went out to the companies in question, and the total is now north of 21,000, according to a spokesman for the organizer, the subtly-named Youbetrayedus.org.
The anti-CISA effort targets companies that signed a September 14 letter to legislators that supports the controversial bill. Executives from Adobe (ADBE), Apple (AAPL), IBM (IBM), Microsoft (MSFT), Oracle (ORCL), Salesforce (CRM), and Symantec (SYMC), and the BSA Software Alliance all signed the letter.
A spokesman for one of the companies involved said the BSA letter does not explicitly support CISA, but stresses the need for stronger cybersecurity protections in general. In a statement posted on Friday, Salesforce said it does not support CISA.
The letter itself urged action on four key legislative areas including cyberthreat information sharing, but that does not refer specifically to CISA, according to the spokesman for one of the companies.
Youbetrayedus.org is an offshoot of the Internet advocacy group FightfortheFuture.org and is also advocating a boycott of Heroku, a popular online software development platform owned by Salesforce.
If the group sounds familiar it’s because FightfortheFuture worked to defeat SOPA, the Stop Online Piracy Act, in 2012 and advocated for net neutrality before the FCC last year. It circulated another online petition against the act in July.
CISA has become the latest front in a battle brought to a head by former CIA hand Edward Snowden’s blockbuster disclosures of government data gathering practices. On one side are online privacy proponents who feel that government and tech vendors have overreached in collecting and sharing consumer data. On the other are those who feel that in this age of terrorism, the government should be able to monitor online communications.
Another advocacy group, the Electronic Frontier Foundation, weighed in earlier this month against proposed CISA amendments.
The proposed changes “fail to address key issues like the deep link between these government ‘cybersecurity’ authorities and surveillance, as well as the new spying powers the bill would grant to companies,” according to the EFF.
This drive for cybersecurity is closely related to surveillance and, as has been reported, the government has already, under the Comprehensive National Cyber Security Initiative (CNCI), paid telcos to spy on customers using their services.
FighfortheFuture agreed, noting that the proposed bill would give tech companies “sweeping legal immunity to share your personal data with the government, enabling more surveillance and violations of civil liberties.”
Increasingly tech companies have to balance demands for user privacy with their own data collection practices and needs. For more on that topic, see the video below:
Subscribe to Data Sheet, Fortune’s daily newsletter on the business of technology.
This story was updated at 2:10 p.m. EDT with comments from a vendor spokesperson refuting the characterization of the BSA letter as being pro-CISA and again on September 25 to include Salesforce.com’s statement.