Though announcement letters more often are meant for correspondence to more than one person, it is not a necessary condition. It is used to announce an event or a decision which may be personal or professional in nature. Professionally, announcement letters are written for various purposes like announcing the quarter financial result to investor; a notice board announcement for an event, policy decision or clarification. It could be a public notice in the print media regarding some professional or personal occurrences including mergers and demergers of business, weddings, engagements or even a demise.
Professional announcement letters should always be written in official letter pad. The name and designation of the announcing authority should be clearly mentioned. Date of the announcement should be clearly mentioned, it could be required for future reference. The tone of the letter could vary depending on the nature of announcement (happy or sad). Whether the news to be shared is of sad or joyous nature it should deliver the message in clear and concise manner. It is advisable to keep the letter absolutely unambiguous to keep follow up queries at a minimum level.
Personal announcement letters in this regard may follow all the conventions of any other personal mail depending on the nature of the audience, media and the nature of the message.