Solution : https://service.sap.com/sap/support/notes/191827 (SAP Service marketplace login required)
Key words : 
transaction code gcx2 application area    gblr, change message class 8n message 001, change message class 8n message 002, change user exit u200, change user exit u210, j1datum le sy-datum, <--delete   j1datum = bkpf-budat + 10, j1datum = bkpf-budat + 8, change validation messages-----------------------------, j1gjahr = bkpf-budat
Related Notes : 
       
| 337153 | SD postings: 10 days validation | 
| 204373 | Collective note: Greek Localization rel. 3.1H | 
| 178573 | Activation of validations | 
| 143246 | SD postings: 10 days validation | 
| 81966 | MM postings: 10 days validation |