Typos happen! And often times, the signer of a contract or payer on an invoice is not who you originally sent the item to. It's no problem to make an update to a contact email address! Just follow these steps below:
Navigate to the contact page for the contact associated with the contract or invoice and click "+ Action"
2. Click in the Email field and update to the desired email address
3. Click "Save"
4. Go back to the contract or invoice and click "Resend". The item will be sent to the new email address (along with any future items)
Note: If a contact has already paid an invoice or signed a contract with the "old" email address, you will not be able to edit their email address. In this case, you can generate a new contract/invoice and send to the new email (generating a different contact record). The other option is for your contact to sign up for a completely free RPC account - then they can manage all of their items in their account and update their email address on their end!