Sender in PO emailed to vendor

Hi,

Here is an issue somwhere between MM and BC (workflow).

Let be a PO created by BUYER (= Sap User) which is not subject to a release strategy sent out to vendor - the sender seen by the vendor in his mailbox is BUYER.

Now when the same PO is subject to a release strategy and workflow applied to PO release activity performed by MANAGER (=Sap User) - the sender seen by the vendor in his mailbox is now MANAGER.

My issue: MANAGER will not be involved in PO follow up with the vendor for the second case of PO and thus should not be shown in the process. A release is an internal (and possibly confidential) process not to be communicated outside the company.

Question: how can I avoid suche side-effect?

Backgroung information: I re-use a standard workflow template WS2...75, SAP is ECC6.