This can easily be chosen from the workers master file on the ‘Web Admin’ tab (which is only available when it has been selected for your user in the ‘Users setup’).
By default all users will be setup to receive all emails immediately, but if an approver is concerned that they are receiving too many emails, you can select the ‘Once daily’ option. This does mean though that the approver must lose the links in the email that can automatically approve individual POs. They will therefore have to go to the website to approve all POs in future.
The emails will be sent daily between 10am and 11am…and will continue to send daily until that approver has nothing left to approve.