The decision followed two complaints filed on April 15 by the Professional Association of Foreign Service Officers against the Department of Foreign Affairs, Trade and Development.
The federal tribunal ruled that Foreign Affairs was wrong to secretly monitor emails between the union and its members, but that the department was within its rights when it ordered its employees to remove an out-of-office message alerting recipients to a "breakdown" in negotiations as the cause for the delay in their replies.
The union represents approximately 1,350 foreign service workers, with the majority, 70 per cent, working at Foreign Affairs. The rest, 24 per cent, work at Citizenship and Immigration, and 3.5 per cent work at the Canada Border and Services Agency.
In his ruling, labour relations board panellist Renaud Paquet "partly allowed" the union's first complaint that Foreign Affairs violated the Public Service Labour Relations Act when it blocked emails sent by the union to its members.
Paquet said Foreign Affairs violated the act "by secretly monitoring all emails sent by the bargaining agent to its members at their work email address between Dec. 2012 and March 2013."
The labour board further ruled that Foreign Affairs also contravened the act "by not giving prior notice to the bargaining agent that it would unilaterally block the bargaining agent's access to its email network on March 22, 2013, without prior notice."
Paquet "partly allowed" the complaint because he disagreed with the union's argument that Foreign Affairs was infringing on its employees rights to freedom of expression by blocking their emails.
The department's "refusal to allow the bargaining agent to use its property to transmit its messages is not a violation of freedom of expression," Paquet wrote.
Paquet "dismissed" the union's second complaint that Foreign Affairs was violating the act when it ordered union members to remove an out-of-office reply and threatened those who didn't comply with disciplinary measures.
In his ruling, Paquet said it was "not unreasonable" for Foreign Affairs to decide what was improper to write in the out-of-office replies.
In fact, the ruling found that Foreign Affairs was "perfectly entitled" to order its employees to remove those messages in their auto replies and threaten disciplinary action if employees did not reply.
Paquet said, in his decision, "there is a significant difference between using the out-of-office reply and wearing union buttons in the workplace to carry a labour relations message related to difficulties or issues at the bargaining table."
CBC's request to the union for comment on this week's ruling went unanswered, and Foreign Affairs Minister John Baird was not available for comment.
This week's ruling follows another decision by the labour board last Friday where it found that the Treasury Board had negotiated in bad faith in its negotiations with striking diplomats.
While Treasury Board President Tony Clement did not immediately respond to the ruling, on Saturday he laid out his interpretation of the ruling in a series of posts on Twitter that ended with him saying, "With hard work, plus a little trust, we can respect the taxpayers and meet some of @PafsoApase's concerns. Thx."
Immigration Minister Chris Alexander issued an official news release, also on Saturday, signalling the Harper government's intention to appeal Friday's ruling with the Federal Court, as a way "to preserve all available options."
On Monday, PAFSO president Tim Edwards said in a news release that the federal government's decision to appeal the ruling will "unnecessarily" prolong what is already one of the longest strikes in federal public service history.
“The government’s actions today bring us no closer to a settlement,” Edwards said.
Foreign service officers have been in a legal strike position since April 2, 2013.
The union representing the striking diplomats has said there is a wage gap of up to $14,000 between diplomats and other government professionals.
Foreign service officers are simply asking the federal government that they receive equal pay, for equal work, the union says.
On Friday, the labour board encouraged both sides to "renew" their attempts at resolving the dispute.