Which element should always be included in the content of an email delivery?

Including a mirror link and an unsubscribe link is essential in the content of an email delivery because these elements are crucial for compliance with email marketing regulations and enhancing user experience.

The mirror link provides recipients with a web version of the email, ensuring that even if they have trouble viewing the email in their email client, they can still access the content through a web browser. This is particularly useful for mobile devices or certain email applications that might not render the email properly.

The unsubscribe link is a legal requirement in many regions, enabling recipients to opt-out of future communications easily. This not only helps maintain goodwill with your audience but also allows for better list hygiene, ensuring that your email list consists of engaged subscribers.

While personalized content, vanity URLs, and HTML scripting may enhance an email's effectiveness or branding, they do not hold the same legal requirement or universal necessity as the mirror and unsubscribe links. Thus, the correct answer highlights the fundamental elements that must be included in every email delivery to meet compliance and user needs.