No, you cannot change the email address on a reservation. The buyer's email address is the one detail on a reservation that cannot be changed once the reservation has been created. It's the identity the reservation, its documents and its ID check are tied to.
This article includes:
Why can't the email address be changed?
Everything on a reservation, from the signed documents to the identity check, is linked to the email address the buyer registered with. Changing it would break that link, so the platform does not allow it.
What can I do instead?
What you can do depends on whether you are a buyer or work for a housebuilder.
If you are a buyer
If you need the reservation under a different email address, contact your housebuilder's sales adviser. They can cancel the existing reservation and create a new one with the correct address.
Any steps already completed will need to be repeated on the new reservation, so ask the sales adviser to download any documents you have already signed before it is cancelled.
Note
If you have already paid your deposit, you will not be asked to pay it again; the housebuilder marks it as already taken on the new reservation
If you work for a housebuilder
Cancel the reservation and create a new one with the correct email address.
Warning
Cancelling deletes everything on the reservation, including signed documents, so download them first and upload them to Supporting Information on the new reservation so the buyer doesn't have to repeat those steps
Note
A reservation can be cancelled at any status, but the Negotiator role cannot cancel, so if the option is missing ask a colleague with a higher role
Cancelling returns the plot to Available and every step is completed again on the new reservation. Steps that do not need redoing can be marked as done: at the deposit step, choose the Already taken or Taken externally option rather than asking the buyer to pay again.
Can other buyer details be changed?
Other details such as name, nationality or address can be amended. See Who can amend a reservation?