The answer is D: announcements for meetings.
Even though the use of email is an accepted professional tool, it must follow a certain tacit etiquette on how and when to be used.
In general terms, an email should be used in professional settings only to communicate or distribute information —in a formal, direct and respectful tone—, to one or many recipients, that is of an impersonal nature. In professional settings, an email should not be used for personal or legally binding situations.
