Transactional writing is writing that is part of a chain of written communication intended to communicate, persuade or inform. Often transactional writing takes the form of letters or emails and is part of a written conversation. Other types of transactional writing include grant proposals and job applications.
Transactional letters should be brief. The best way to write them is to plan them out before committing them to paper or screen. Typically they include a short opening paragraph thanking the recipient for their prior communication. A transactional letter usually contains two main paragraphs, one to establish the topic and the second to elaborate on it. The ending is brief and formal, as befits a professional communication.