"Dear" followed by the title of the recipient, such as Ms., Dr. or Professor, is one of the most common salutations for letters and e-mails. The salutation "Hi" should only be used for close friends and family.
When unsure of the recipient's gender, the first name and last name are included in the salutation. For instance, "Dear John Doe." If there are two recipients (husband and wife), the salutation, "Dear Mr. and Mrs. Smith" is acceptable. The salutation is followed with a colon or comma, and then a space before starting the first paragraph of the letter or email.
Other common salutations are: "Greetings" "Good Morning/Afternoon" and "Good Day" followed by the name of the recipient. This form of salutation is more formal. When addressing a group, particularly in an email, a common salutation is "Greetings All." In this case, the highest degree of courtesy is used.
Generic salutations like "Dear Sir/Madam" or "To Whom It May Concern" should be avoided. Using such salutations could indicate that the sender did not take time to find out any details about the recipient.
For some business professionals, salutations also refer to the closing statement in a letter or email. Some common closing salutations include "Respectfully yours," "Sincerely yours," "With many thanks" and "All the best."