2503936 - Sender e-mail of S/4HANA Output Control output is unexpected. And "sender email address can't be initial" when manually adding output

Symptom #1.:

You create a new output into an existing purchase order (PO), even other outputs already there (and they probably outputted already). You notice that when such output (like the one what you entering now manully) automatically determined via S/4HANA Output Control then no problem appears, but when you maintain the output manually the "sender email address can't be initial" message appears at leaving output messages screen.

Symptom #2.:

You have a purchase order into which you make a S/4HANA Output Control output trigger with email medium, and you notice that its sender is an unexpected mail address in SOST after the output is processed.

S/4Hana with S/4HANA Output Control

output, nachricht, BRFPlus, Addresse, Anschrift, ME21n, ME22n, ME32k, ME42, ME32l, BRF+ , KBA , MM-PUR-GF-OC , Message determination and printing , MM-FIO-PUR-PO-OM , Purchase Order Output Management , Problem