2599578 - Create Attachment with .csv extension, SO424 Error occurred during import / 1R557 Content-Type msexcel2 is not permitted

When create attachment with .csv extension via transaction SBWP, SO00 or SO01 -> New message, an error occurs with

• Message number
  SO424 Error occurred during import
  
  
• Message number in SLG1:
  1R557 Content-Type msexcel2 is not permitted
  
  

• Release 700 or higher
• SAPOffice

SO00, SO01, SO424 Error occurred during import, 1R557, Content-Type msexcel2, is not permitted, Error occurred during import, An error occurred, during the import of a file, The Content-Type is not permitted , KBA , BC-SRV-COM , Communication Services: Mail, Fax, SMS, Telephony , BC-CI-WEBR , WebRFC, WebReporting , Problem