Solution : https://service.sap.com/sap/support/notes/1050688 (SAP Service marketplace login required)
Key words :
quoted-printable-coded smtp headers, sap internet mail gateway 4, internet mail gateway, quoted-printable decoding, quoted-printable coding, symptom underscores '_', underscores '_', subject lines, incoming mails, ascii characters
Related Notes :
| 101573 | Internet Mail Gateway: Versions |