Some diplomats said they joined the dissent by sending an email saying “I’m in” or “Please add my name as a signer” along with their full name, title, position and post.

The letter was apparently circulated through informal networks of diplomats and not through any State Department-wide email list. One diplomat on vacation in the United States said he received the letter from a colleague in another part of the world who was not connected to the drafters and was simply passing it along.

The diplomat predicted that hundreds of other diplomats would be eager to sign it if they could, but because of the complications of figuring out where the dissent memo originally came from, he was not sure how many would actually sign it.

Most people in the State Department have never seen anything like this, the diplomat said. He said dissent memos were reserved for major policy issues, not for little grumbles like bad food in the embassy cafeteria.

That diplomat also requested anonymity, saying that Foreign Service officers were not supposed to criticize American policy publicly and that he did not want to open himself up to accusations that he had violated the rules. That could threaten his job, he said, especially in such a polarized environment.

This is exactly what the dissent channel, as it is called, was intended for.

Starting in 1971 during the Vietnam War, the channel encourages department officials to voice their criticisms internally through a process of sending a memo or a cable to the secretary of state expressing their concerns and suggesting solutions. The final part of the visa ban memo lays out detailed alternatives, including increased vetting for specific nationalities.

State Department rules are supposed to protect dissenters from being retaliated against, and last year several dozen diplomats signed a dissent memo criticizing American policy on Syria.