When Canadian columnist Anthony Furey received an email said to be from Twitter's legal team telling him he may have broken a slew of Pakistani laws, his first instinct was to dismiss it as spam.
But after Googling the relevant sections of Pakistan's penal code, the Toronto Sun op-ed editor was startled to learn he stood accused of insulting the Prophet Mohammad - a crime punishable by death in the Islamic republic - and Twitter later confirmed the correspondence was genuine.
His perceived offense was to post cartoons of the prophet several years ago.
Furey and two prominent critics of extremism in Islam say they are "shocked" to have received notices by the social media giant this past week over alleged violations of Islamabad's laws, despite having no apparent connection to the South Asian country.
They say the notices amount to an effort to stifle their voices - a charge Twitter denies, arguing the notices came about as a result of "valid requests from an authorized entity," understood to mean Pakistan, helped users "to take measures to protect their interests," and the process is not unique to any one country.
But Furey is the third prominent user in the space of days to publicly complain about receiving a message linked to Pakistan.
The other two are Saudi-Canadian activist Ensaf Haidar and Imam Mohammad Tawhidi, a progressive Muslim scholar from Australia who was born in Iran.
Both are outspoken critics of religious extremism and have accused the social media giant of helping to silence progressive ideas within Islam.
'Validates blasphemy laws'
Furey, who detailed his experience in a column for his newspaper on Saturday, told AFP: "I'm somewhat alarmed that Twitter would even allow a country to make a complaint like this, as it almost validates their absurd blasphemy laws."
The tweet in question was a collage of cartoons of Mohammad that he posted four years ago.
"Looking back, I remember I did it right after there had been an ISIS-inspired attack in retaliation over the cartoons," Furey wrote in his column, adding he had not posted similar material before or since.
Haidar, who is the wife of Saudi writer Raif Badawi who was jailed in his country in 2012 for charges including apostasy, told AFP: "I'm very shocked by Twitter. They want to silence any voice telling the truth."
Twitter wrote to her concerning an August tweet which showed a woman wearing the Islamic full veil, with the caption: "Retweet if you're against niqab."
A notice sent to her and seen by AFP advised her that Twitter had received official correspondence saying she could be violating Pakistani law for the tweet, adding: "You may wish to consult legal counsel about this matter."
Tawhidi meanwhile was sent a similar notice flagging a tweet that called on Australian police to investigate extremism in mosques following a deadly knife attack in Melbourne in November.
The scholar attached the legal notice sent to him by Twitter informing him of possible violations of Pakistani law, and tweeted: "I am not from Pakistan nor am I a Pakistani citizen.
"Pakistan has no authority over what I say. Get out of here."
Reached for comment, a spokesperson for Twitter told AFP: "In our continuing effort to make our services available to people everywhere, if we receive a valid requests from an authorized entity, it may be necessary to withhold access to certain content in a particular country from time to time."
The spokesperson added: "We notify users so that they have the opportunity to review the legal request, and the option to take measures to protect their interests."
Pakistan has previously threatened to block Twitter if the company did not remove content its government found offensive.
It banned Facebook for hosting allegedly blasphemous content for two weeks in 2010 while YouTube was unavailable from 2012 to 2016 over an amateur film about the Prophet Mohammad that led to global riots.
Furey told AFP that although he was taken aback by the notice, "I'm at least glad they brought it to my attention that the Pakistan government has their eye on me."
But he added: "One troubling consequence to all of this is that even people in countries without these blasphemy laws may start to self-censor for fear of the reach foreign governments will have over them in the online world."