As you maybe know, when more than one server are using the same SID it can keep from sending emails from OWA (Exchange 2010)
This is exactly what we've been living with recently. Both DCs (VM) we using the same SID. But each Exchange server had a unique SID.
So I demoted a DC. Then a new VM has been created. This time Windows 2008 R2 has been installed from the CD, no image, no sysprep, nothing. I ran DCPROMO.
But the new server has the same SID ! How come ? It has a different name, it comes from a fresh Windows installation. I don<t get it but maybe someone knows ?
However, Exchange is no longer preventing the emails to to be sent out.