Approve PR through email in SAP R/3 system

Hi,

I got a specific requirement from my client related to Purchase Requisition Approval Workflow.

If an approver is unable to log on to the R/3 system (i.e. while traveling) and can only access his email can he approve the PR from his email only?

Means is there a way in SAP R/3 system to carry out the above requirement?

Please suggest.