Electronic receipts (e-receipts) can be forwarded to email@example.com from the email associated with your Ramp account. You can send multiple receipts in the same email (as PDF or images) if you wish. You can also accept receipts from other email addresses. Go to your profile and click "Manage Profile" to add each address you want to accept receipts from.
You can also set up automatic forwarding of email receipts. Read more about that here.