hone calls, memos (whether sent as hard copy or e-mail transmissions) are the primary means of in-house communication in American business. Memos convey queries, comments, replies, announcements, policy statements, direction, statistical information, clarifications, reminders, authorizations, and a host of other routine but vital communications. Many business writers manage to ruin memos through casual, thoughtless mistakes. Their errors fall into four categories. Make sure you avoid each in your own Writing.