First off, create fake appointment/s for your lead/s on your calendar.

Make sure that the date you'll use is a week before you intend to send your come back email to your leads.

Once the appointment/s have been created, go to Settings > Email & Texts.

Under the Email Templates, click on the Come Back tab.

Set the Send come back emails to One week after customer's last appointment.

Don't forget to hit the Save Changes button at the bottom.

Create a Mailchimp account. If you already have one, proceed to the next step.

If your Mailchimp account is not yet integrated with your ZenMaid account, check out this article.

Once integrated and your customers/leads have been synced, you may now log back in to Mailchimp and send blast emails or promo emails even.