CONTRACT VIA EMAIL CORRESPONDENCE
Email correspondence is just as binding as a signed contract when negotiating assignments. You have to remember to state your terms of delivery very clearly. If the negotiation drags on a lot, it may be reasonable to send the customer a clear summary of everything agreed upon.
It’s worth saving the emails, as it’s easy to verify what has been agreed and with whom, should there be any problems. They also serve as a reminder to yourself about what you promised and when.