linking sap to external application(eg. lotus notes,outlook express)

hello everyone,

ii have created a workflow for PO Release and its working fine. i have triggered a mail when a po is created to respective agent both in sap inbox as well in Lotus notes . now my requirement is to create a link in lotus notes when the message is received in lotus which will directly release PO from lotus notes. can any one tell me the steps i need to do for the same.

Regards,

Pradeep