The phrase "a simple letter" is correct and usable in written English.
You can use it when referring to a letter that is straightforward, uncomplicated, or lacking in complexity.
Example: "I decided to write a simple letter to express my gratitude for their support."
Alternatives: "an easy letter" or "a straightforward letter".
Instead I found a simple letter outlining his principles for being successful as a Marine Corps attack pilot.
"A simple letter that says thanks tells a Marine that somebody back there cares," Major Bourland said.
The reality is that trying to make representations to social services of duties to children isn't just a [matter of] a simple letter.
A simple letter along the lines of "I am writing to apply for the position advertised in the journal dated... .. would be completely unacceptable in France.
It was a simple letter from the American president to the German president, wishing his country well on the 12th anniversary of Germany's reunification.
The first fund-raising effort, a simple letter offering membership in a museum that existed only in theory, brought in $500,000.
We present evidence that a cognitively challenging working-memory task is followed by greater activation of the DMN than a simple letter-matching task.
In order to demand that a debt collector or recovery agency validate a debt, you need only to send a very simple letter to the agency that is attempting to collect.
About two weeks or so before the prom/dance, construct a sweet, simple letter asking your crush to go out to the prom/dance with you.
We'll start with a simple capital letter: "L" We'll start with a simple capital letter: "L" Draw an outline around the letter (lightly with a pencil), and make sure to do two things: Draw an outline around the letter (lightly with a pencil), and make sure to do two things: Make the outline with no sharp corners or angles, for now.
This can be a pre-made form or simple letter stating that you are rescinding the contract.
