Putting the Unsubscribe Link at the top of the message
ISPs want to ensure it is easy for their customers to unsubscribe from your messages. For this reason, they prefer that list owners include the unsubscribe link at the top of the message.
Example of Unsubscribe Link
Placing an unsubscribe link at the top reduces the chances of subscribers clicking the "spam" button in case they don't want to receive your messages. Hitting the spam button can create deliverability issues with your messages. It's best to have the unsubscribe option easy to find.