A glass-enclosed venue reaching out into the Atlantic played host last month to “The Magic of Opera,” a gala celebrating the 25th anniversary of Opera Maine.

Guests paid as much as $2,500 for cocktails, dinner, music and a live auction. An invitation from the Portland-based opera company recommended “Black tie or festive attire.”

In the view of one purported attendee, that instruction wasn’t strict enough.

In a letter published in the Portland Press Herald on Saturday, someone writing under the name “Crawford Williamson” complained about the sartorial standards of the gala-goers. “Slovenly clothing, behavior mar enjoyment of Opera Maine Gala,” blared the headline.

The grievance, ultimately erased after it was revealed this week to have been aired under a pseudonym and possibly also intended as satire, nonetheless touched off a spirited debate about culture, class and respectability in a rapidly changing city. It turns out that some in the maritime community have values pointing their sails in other directions. Not everyone is interested in keeping up with the Crawford Williamsons of the world.

The author did not want to be misunderstood. “The Magic of Opera,” the fashion whistleblower wrote, “was superb!” Proceeds from the event will fund the company’s production this year of Mozart’s “The Magic Flute.”

The problem, however, was the loose interpretation of the black-tie dress code, a requirement from which attendees strayed as if seduced by the Queen of the Night.

“Clearly, this phrase is foreign to many Portland residents,” the letter stated. “Several attendees appeared dressed more appropriately to attend one of the local county fairs.”

The letter offered an exception for “some persons, such as the individual with Down syndrome dressed in jeans, tennis shoes and no jacket.” But for everyone else who “dressed like they have zero care,” the person wrote, woe unto them for spurning dinner jackets, cocktail dresses, floor-length gowns, bow ties and cummerbunds.

Attendees went instead with more comfortable dress, as they do at cultural events across town, wearing “tennis shorts, torn jeans and coveralls.” Sometimes, they even don baseball caps, the letter announced breathlessly, claiming “this behavior is perceived as disrespectful to the performers and demonstrative of lack of self-worth on the part of the individuals who choose to dress as farmworkers.”

The problem wasn’t one of attire alone.

“Then the table manners,” the letter continued. “Some guests appeared to have been taught how to eat by farm animals.”

The breaches of etiquette were all evidence, to the letter’s author, that life in Maine’s most populous city and economic hub came with drawbacks.

“When we moved to Portland, we realized we had landed in Hooterville,” the writer complained.

The waterfront community, which boasts new culinary and artistic attractions, was making “some strides” toward becoming a “true city,” the letter concluded. To reach that end, however, residents had to “show self-worth and dignity,” the author reasoned. “Otherwise, Portland will always be a backwater town.”

The letter became a local cause celebre, rocketing to the top of the Press Herald’s website during the weekend as readers offered feedback for the author — and for the newspaper that had aired the haughty observations.

“Wow, this is a rotten letter,” one woman wrote on Facebook, labeling the viewpoint “pretentious.” Maine’s beauty, she added, is that the same event will feature both “sequin gowns and jeans.” She directed the author to one of the highest-income urban areas in the country, which is located in Philadelphia, writing, “Perhaps you need to go back to Rittenhouse Square.”

Another resident celebrated the denim-wearing operagoer, noting that such a person would be more likely to talk to her before the performance or during intermission than would the chic “gentleman,” she wrote, who is “an elitist and certainly not a ‘gentle’ man.”

A violist who performs with the opera company weighed in as well, assuring readers that she and her colleagues were “grateful that you have come to hear us perform, regardless of your attire.”

“I‘m pretty sure the style or cost of the clothing you are wearing has no bearing on how the music will affect your soul,” wrote the musician, Kimberly Lehmann.

While some said they agreed with the author’s advice — though they could do without the “condescension” — others said the account of Portland missed the mark.

They cherished the “backwater” aspects of the city, the hometown of Henry Wadsworth Longfellow, whose poems warned of seeing life as only about material acquisition. In that spirit, a reader said she resented “folks in top hats” dictating the terms of “high culture.” She offered an alternative possibility: “Maybe we’ll create dynamics not based on socio-economic strictures? Imagine!”

There were more practical problems with the letter. No one with the author’s name had attended the April 28 gala, as the leaders of Opera Maine noted in a letter to the editor published in the Press Herald on Monday. They also told Boston.com that no one at the show had Down syndrome, though such a guest would have been “heartily welcomed.”

The letter from the opera company replaced the polemic from “Crawford Williamson,” which was taken down.

In an editor’s note, the newspaper said it had been “misled by the author of the letter, who twice gave us a fake name.” The paper’s “standard verification process” had failed.

“We are troubled by this incident, and we are revising our protocols for verifying letters,” the editors pledged.

The opera’s top managers, in their letter, assured readers, “We don’t care what you wear.” They called the original commentary “mean-spirited” and criticized its author for lacking the “courage to sign his or her name.”

“Crawford,” they said, was wrong. “No one ate like a farm animal, or wore overalls or a baseball cap,” they wrote.

“But guess what?” If they had, these guests still would have been welcome. “Opera lovers are diverse and Opera Maine strives to be a welcoming and inclusive organization — onstage as well as in the audience,” the letter stated. “Our mission is to share the beauty and power of the operatically trained human voice with everyone.”

To patrons planning to see “The Magic Flute” this summer, the opera counseled, “please come dressed however you wish! Be comfortable!”

In fact, the gala was part of fundraising efforts that succeeded in securing enough money to offer free tickets to anyone 25 and under for a pair of July performances.

In Portland, it’s still possible to hear the high notes in the Queen’s second aria without a high-dollar ticket and couture to match. Some residents would like to keep it that way.

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