Hi All, When i starts the msi installer, then i start it as "NT Authority\System" (it's independent from the current credentials...). I made many identity manipulation, but without any hit. When i try to make the windows impersonation, then the exchange cannot accepts my request, because the exchange cannot accepts any request (what entails an active directory modification) from impersonated user... How can i resolve this problem? (i have another thread in the exchange development, but i believe it in that manner, this rather here owes.) Thanks for all! Imre Kovcs