Hi Kul
It seems to be right as you said. "" a manual change in ECC of any field will tag the document address as manually changed in GTS"". I tested.. and the system is considering manual changes in ECC of all field in documents business partner address tab and blocks the document.
This partner is in spl list. But the screening does not seem to happen for fields email id , telephone no.
But when the same is changed.. system blocks the document...