I often have receipts emailed. Copy and paste would make it easier.
There are two potential ways to achieve this.
Save the unique email in tray address to a contact on your phone. When you receive the email receipt, hit forward to this address.
When you receive the email receipt, save the receipt to the camera roll, then when you are in the capture app, select the receipt from the camera roll and send to the In tray.
MYOB Capture Team.