The phrase denotes an email that directly references a preceding dialogue, whether oral or written. Such correspondence frequently aims to solidify decisions, document agreements, or provide updates related to the earlier exchange. For example, after a telephone call discussing project timelines, a subsequent email might begin by referencing the call and then proceed to outline the agreed-upon milestones.
The practice of referencing prior conversations in email communications offers several advantages. It enhances clarity by providing context, minimizing potential misunderstandings. Additionally, it creates a traceable record of decisions and agreements, proving useful for future reference and accountability. Historically, this practice stems from the need to formalize informal discussions, particularly in business and professional settings.