"flimsy letter" is correct and usable in written English.
It means a letter that is weak or lacking in substance. Example: The judge dismissed the case because the evidence presented was only a flimsy letter from the accuser.
In a takeoff on the Hollywood sign, her images record her temporary outdoor installations, in which large, flimsy cardboard letters spell out words in empty landscapes.
After reading, in quick succession, four books about the men who fought the war, I took out a box of flimsy, yellowing letters, and tried yet again to imagine what my grandfather went through.
Occasionally, despite my best efforts, a shred of his inextinguishable past turns up to tease me: a page of one of his typed letters on flimsy airmail paper, for instance, advising me of some crazy scheme he wants me to "bring to the Attention of your Advisors with a View to Early Investment".
Dach's attorney has long objected to the Post's willingness to cite an anonymous agent, arguing in his January letter that the account "is particularly flimsy unless corroborating evidence exists".
"In the warm sun the haul seemed disappointing: a brass desk lamp, cream-colored paper with some handwriting on it, blank letterheads, flimsy telegrams typed on Germany Navy signals forms, and a letter dictated to 'my dear Heinrich.'" At war's end, Bradin brought the documents home with him to South Carolina.
Mr Robertson described the wording of the letter to Mr Downey as ambiguous and "weak and flimsy".
And up the steep mountainsides stand hundreds of flimsy structures composed of USAid plastic sheeting and grain sacks, the letters and logo faded.
(The report's conclusions were first widely publicized in a November story in Science, and the flimsy basis for the "very high" statement in the 2007 report is detailed here, in a letter to Science by a Canadian expert on glaciers.
Instead they read comics, shoulders hunched to protect the flimsy covers from the wind, puzzling out the last dram, the last square inch of information, the credits, the letters page, the copyright, the Sea Monkeys ads, the insult that made a man out of Mac.
