Letters of enquiry are a written declaration of interest in a job, product, service or resource. Their basic components are salutations, an introduction paragraph that expresses the author's specific intentions, follow up paragraphs that state the reasons why the writer is writing and a final paragraph that concludes the letter with an expression of gratitude. The University of Washington's official website has examples of letters of enquiry.
All letters include the date and contact information of both parties in the upper left-hand corner. A brief heading with the specific item of interest is sometimes included prior to the introduction paragraph but after salutations. Depending on the request or area of interest, letters of enquiry vary in format. Letters intended for acquiring a job position include a note regarding an enclosed resume in the second paragraph, in addition to the actual resume.
Both enquiry and inquiry are correct spellings for the same word with the same meaning. The former is used more often in the UK while the latter is an American word. Additionally, enquiry is sometimes distinguished from inquiry by its use as an informal query, while inquiry is meant to express the launching of a more formalized examination of matters.