Which type of correspondence consists of any letter or memorandum sent to an addressee outside the activity that concerns a matter within the cognizance or official interest of the activity?

The type of correspondence that refers to any letter or memorandum sent to an addressee outside of the activity, concerning matters of official interest, is known as official correspondence. This type of correspondence is essential for maintaining formal communication and ensuring that the information is relayed according to established protocols and standards. It is tailored to convey official positions, policies, or requests that represent the organization's outcome, thereby serving its operational needs.

In contrast, command correspondence is generally focused on directives and orders from higher authority within the organization, while informal correspondence is more casual and often does not adhere to strict formalities. Personal correspondence pertains to private matters and does not involve official business. Therefore, official correspondence best encapsulates communication of this nature, designed specifically for external engagement on the activities' official matters.