Emre Bey merhaba;
Sorunu aşağıdaki yöntemle çözmeyi başardım
delete watermark from HKLM\software\microsoft\exchange\8.0\client access

Goto Exchange Shell and run the following commands replacing server2 with your servername.
remove-autodiscovervirtualdirectory -identity "server2\autodiscover (default web site)"
remove-oabvirtualdirectory -identity "server2\oab (default web site)"
remove-owavirtualdirectory -identity "server2\owa (default web site)"
remove-owavirtualdirectory -identity "server2\exchweb (default web site)"
remove-umvirtualdirectory -idenity "server2\unifiedmessaging (default web site)"
Remove-ActiveSyncVirtualDirectory -identity "server2\microsoft-server-activesync (default web site)"
remove-webservicesvirtualdirectory -identity "server2\ews (default web site)"

run exchange setup.
fakat şimdi de owa sayfasına bağlandığımda sertifika hata sayfası gelip devam et dediğimde boş bir sayfa açıyor.