Editorial guidelines should cover a wide range of topics to be comprehensive: 1. Tone and Voice: Define the brand's voice. Is it formal, casual, or somewhere in-between? 2. Grammar and Style: Specify grammatical rules and style preferences. For example, should you use the Oxford comma? 3. Content Structure: Outline how each email should be structured, including sections like the subject line, preheader, body content, and call-to-action (CTA). 4. Visual Elements: Provide guidelines for the use of images, fonts, and colors to ensure they align with your brand identity. 5. Legal Requirements: Include compliance guidelines for data privacy laws and unsubscribe options.