Managing AdobeSign Email Volume For Many Approvals

Is there a way to reduce the number of emails an approver would get in a high volume environment?  We use AS for accounting approvals and send a large volume of items daily.  Currently we send them in a large batch (dozens of invoices) with signature lines on each, but this has presented a problem as the approver cannot reject one item without rejecting the whole document.  This happens fewquently.  If we were to send items individually it would bury the approvers in emails.  Is there a way to forego the individual emails and send out a summary approval request at the end of the day (or some designated time)?

Conversely, is there a way to allow an approver to reject a single attachment and approve the rest?