2746771 - Server not responding OK to MAIL FROM; xxx x.x.x Client was not authenticated

• A Process Integration (PI) or Process Orchestration (PO) mail adapter is being used at the receiver side to send emails to the target mail server.
• During the processing, mail adapter is trying connecting to target SMTP server but it fails with the error:
  Message processing failed. Cause: com.sap.aii.af.sdk.xi.srt.BubbleException: Failed to call the endpoint [null "null"]; nested exception caused by: java.io.IOException: server not responding OK to MAIL FROM; xxx x.x.x Client was not authenticated

• SAP NetWeaver
• SAP Process Integration

Exchange Infrastructure, Process Integration 7.0, PI 7.0, PI 7.01, PI 7.02, Process Integration 7.10, PI 7.10, Process Integration 7.11, PI 7.11, Process Integration 7.30, PI 7.30, Process Integration 7.31, PI 7.31, Process Orchestration 7.40, PI 7.40, PO 7.40, Process Orchestration 7.50, PI 7.50, PO 7.50, NetWeaver, XI, AEX, Mail Box, authentication, sender, receiver, SMTPClientConnection, SMTP, Simple Mail Transfer Protocol , KBA , BC-XI-CON-MAI , Mail Adapter , Problem