The unsigned letter was from a nationalist accusing George (not his real name) of being heavily involved in loyalist roadblocks, and announcing a Catholic boycott of his shop.
It was no idle threat; nearly two weeks on and the Protestant businessman has seen his trade almost halved.
"My customers were about 50-50 Protestants and Catholics," said George, who lives and works in the small town of Castlederg, Co Tyrone, a few miles from the Irish Republic.
"Since the week of Drumcree I have had hardly any of my Catholic customers in - I reckon my trade has gone down by more than 40 per cent. At first I thought it might be down anyway because of the holiday period - but now it's clear they are staying away."
George is not alone. At least seven other Protestant businessmen in the town have received the same letter - always ending "yours disappointed" - which bears the sign of an orchestrated campaign.
In nearby Omagh, where a Protestant dry-cleaning business was burnt down, there was an even more ominous letter in a local Catholic newspaper. It finished: "Do not spend your money in support of Orangemen and their Orange Order. Buy only from Catholic businesses and invest in your own people - the only people who truly want full civil rights and a future for Catholics in these northern counties."
It was signed "General Boycott".
The word carries a heavy historical resonance in the island of Ireland, emanating from the eponymous Captain Boycott, one of the principle victims of tenant farmers withholding rent and co-operation in the last three decades of the 19th century.
George, who denies helping with the loyalist roadblocks which caused disruption locally during the Drumcree siege, is shocked and bemused by its return.
"I thought 'boycott' was the language of the past. I have been in business for 25 years and I have not come across this kind of thing before.
"The sadness is that Castlederg is not noted for actions like this - we have a good spread of people from both communities."
The danger now is of Protestant retaliation. "You could see things turn the other way," said George, "and people could boycott Catholic businesses. I wouldn't like to see that - it would not be very helpful."
Perhaps inevitably, some Protestants are urging a tit-for-tat severing of all ties with the Republic - a reflection of the view that the boycott is being whipped up by "outside elements".
A local Ulster Unionist councillor, Derek Hussey, calls the letters "sinister" and adds: "I do believe they are part of something organised, probably from outside the area."
However, Social and Democratic Labour Party councillor, Joe Byrne, from Omagh, while condemning the boycott, thinks loyalists simply do not understand the depth of Catholic feeling provoked by the week of unionist civil actions during Drumcree. These included the roadblocks, which were often tolerated by the Royal Ulster Constabulary.
"Basically nationalists without strong political affiliations have felt almost exasperated. They have seen that the institutions of state, such as the police, do not act even-handedly."