Basically, and you should not be too surprised at this, the permission for BES admin are really really close to the permissions necessary for inserting holidays or running a full-state calendar migration.
Check out this post:
which advises setting permissions as follows:
BESAdmin –role ViewOnlyAdmin
BESAdmin –accessrights ExtendedRight –extendedrights Send-As, Receive-As,
And then tells you to follow up with:
Open Active Directory and from the View menu select "Advanced Features". Then
go to each user that will be added to the BES and open their properties, go to
the security tab and add the user BESadmin and add the security permission "Send
As". (This will overcome some MS patches that prevent BES sending emails).
Methods are available to add BESadmin "Send As" rights to all users if required
but this method ensures only the required users have permissions added.
Make BESadmin a local Administrator of the server where you will be
installing the BES software. This is done by right mouse clicking my computer
and selecting “Manage”. From Computer Management expand “Local Users &
Groups” and select Groups. From Groups double click “Administrators” and add
This is pretty much what we tell you to do in setting up a service account for running a Sumatra migration or inserting holidays, checking for broken meetings, or running the "terminated user" option in our code.
If you do not have a specific service account set up yet, this is a good place to start.