Final answer:
The statement is true as proofreading should indeed occur after the content of a message is final. Proofreading ensures the text is error-free, while editing focuses on sentence-level corrections and improvements.
Step-by-step explanation:
The statement that proofreading should take place only after the content of a message is in its final form is true. Proofreading is a critical final step in the writing process, ensuring that the text is free of errors and presented as intended. As part of proofreading, you should read your message to make sure all necessary information is included and clear, use spell check, manually check for correct word usage, and verify the recipient's address. Editing and revising are tasks that happen before proofreading, aligning the content and structure with the purpose of the message.
Moreover, editing is performed at the sentence level, dealing with phrasing, grammar, mechanics, and wording. Reading your work aloud or having your device read to you can help identify areas that do not sound right, thus indicating places that require editing. It is important to note that editing suggestions given by software should be reviewed to ensure they fit with the context.