When this retired English teacher received a letter from Trump, she got out her marking pen.

When retired high school English teacher Yvonne Mason received a letter from President Trump, she did what came naturally.

She got out her favourite purple pen and entered “grading-paper mode”, leaving corrections and comments all over the letter bearing President Trump’s signature.

“Have y’all tried grammar & style check?” she wrote at the top of the page.

“OMG this is WRONG!”

The letter, printed on official White House stationery, was addressed to 61-year-old Democrat Yvonne Mason, who had written to President Trump asking him to visit the families of those who died in the February Parkland, Florida school shooting.

"I had written to them in anger, to tell you the truth," Ms Mason told The New York Times. "I thought he owed it to these grieving families."

Ms Mason, who taught Advanced Placement English language and composition, said the letter did not address her concerns for the grieving families of Parkland.

Instead, President Trump listed the actions the US government has taken in the aftermath of the shooting, including the introduction of the STOP School Violence Act, a bill that has been criticised for its failure to mention gun control whatsoever.

Disgruntled with Trump's response, Ms Mason went to town with her purple pen, making corrections and comments before posting a picture of the corrected letter on her Facebook page and mailing it straight back to the White House.

"It was poorly worded missive," she said. "Poor writing is not something I abide. If someone is capable of doing better, then they should do better."

Among the corrections, Ms Mason "focused mainly on mechanics", circling multiple capitalisation mistakes – including some clearly mentioned in the US government's style guide, which Ms Mason helpfully wrote a link to on the bottom of the letter.

"When you get letters from the highest level of government, you expect them to be at least mechanically correct," Mason told the Greenville Newspaper.

Ms Mason has written a postcard to the White House every day this year, as part of her New Year's resolution.

She said Trump's letter was a far cry from the "beautiful" letters she has received from other politicians.

"If it had been written in middle school, I'd give it a C or C-plus," she said. "If it had been written in high school, I'd give it a D."