A. Using clear subject lines
B. Proofreading before sending
C. Including personal opinions
D. Using a polite closing
Answer: Including personal opinions
A. Using clear subject lines
B. Proofreading before sending
C. Including personal opinions
D. Using a polite closing
Answer: Including personal opinions
Additional Information: Professional emails should focus on the topic at hand, avoiding unnecessary personal opinions.
Subjects: Professional Writing, Business English