Within your Stripe dashboard, you can configure email receipts to be sent to your customers directly from Stripe. To enable and customize receipt emails go to Settings → Email Receipts.
Stripe allows you to customize the icon and header background color of the emails by going to Settings → Branding.
See Stripe docs about customizing email receipts further.
To view or send email receipts within individual Stripe test payments, open the test payment in Stripe that you want to view or send from and look for the View Receipt and Send Receipt links in the Receipt history section.
Stripe only sends email receipts for payments that are made with your live API key or through your live dashboard, so if you are expecting an email for a test transaction, one will not be sent.You can also use your own domain (instead of stripe.com) when sending emails to customers. See Stripe docs for setup instructions.
Do Stripe’s built-in email receipts not provide enough customization for you? Did you know you can also use Stripe and Zapier to send plain text emails to customers (and custom email notifications to site owners) for Stripe payments?