Dozens of unionized Boston Herald staffers are boycotting Twitter to protest a reporter’s suspension after he violated the newspaper’s social media policy with a tweet.

Chris Villani, a general assignment reporter, was suspended without pay by the newspaper after tweeting breaking news in late April following the suicide of former New England Patriot Aaron Hernandez, according to two people in the Herald’s newsroom.

Villani’s tweets have since been made private. But according to Boston magazine, which first reported on the suspension, Villani tweeted this on April 20:

“The notes found in #AaronHernandez cell were letters to his daughter & fiancee, saying he loved them & would see them in heaven, per source.’’

Various local and national media outlets, including the Globe, also reported on Hernandez’s suicide notes. But according to the Newspaper Guild of Greater Boston, which represents Herald reporters, Villani’s report on Twitter violated the Herald’s social-media policy, which includes a provision that reporters must not “tweet, re-tweet or otherwise post ‘breaking news’ or share work in progress without the express approval of the Executive Editor or his designee.’’

The union said Villani’s suspension was the first disciplinary action under the social-media policy since it was introduced in 2013, even though reporters had often tweeted breaking news without an editor’s approval. The union criticized the policy as impractical and cumbersome at a time when breaking news and live events are often first reported on social media before being posted online by media organizations.

“The company is now enforcing a policy that says all news-related tweets and posts must be cleared by an editor,’’ the union said in a statement. “This is not workable for media in a technologically sophisticated and competitive market, when reporters are at a press conference, covering courts, sports or a breaking-news event such as a fire.’’

Villani’s three-day suspension began Monday. At least 45 Herald guild members with active Twitter presences have boycotted the platform this week, replacing their profile pictures with a black box, until he returns to work on Thursday.

Villani did not immediately respond to a request for comment. In an e-mail, Herald editor Joe Sciacca said: “I won’t comment on personnel issues because I don’t think that would be fair or appropriate.’’

However, Sciacca issued a statement to Boston magazine, saying the newspaper’s policy is intended “to keep faith with readers that all of the content we present across all platforms is credible, having been vetted for accuracy and reliable sourcing by editors.’’

“Particularly in this era of fake news and unattributed speculation, the media must do all that it can to earn the trust of those who depend on its reporting,’’ Sciacca’s statement read.

The Globe’s social-media policy contains no particular guidelines for reporters when it comes to breaking news, but says: “Tweeting breaking news is an ongoing reporting process that requires Boston Globe to frequently update or correct tweets as new information becomes available.’’

Adam Vaccaro can be reached at adam.vaccaro@globe.com. Follow him on Twitter at @adamtvaccaro.