Script repository

$fullAccessUsersAttribute = "adm-CustomAttributeTextMultiValue1" # TODO: modify me

# Get DNs of delegates
try
{
    $fullAccessUserDNs = $Context.TargetObject.GetEx($fullAccessUsersAttribute)
}
catch
{
    $Context.LogMessage("Property $fullAccessUsersAttribute is empty.", "Warning")
    return
}

# Create an instance of the 'AdmExchangeMailboxParameters' class.
$mailboxParams = New-Object "Softerra.Adaxes.Adsi.Exchange.AdmExchangeMailboxParameters"
$sendAs = $mailboxParams.SendAs
$sendAs.OverrideOldValues = $False
$mailboxRights = $mailboxParams.MailboxRights

foreach ($fullAccessUserDN in $fullAccessUserDNs)
{
    # Get delegate SID.
    $fullAccessUser = $Context.BindToObjectByDN($fullAccessUserDN)
    $fullAccessUserSid = New-Object "Softerra.Adaxes.Adsi.Sid" @($fullAccessUser.Get("ObjectSid"), 0)

    $objReference = New-Object "Softerra.Adaxes.Adsi.AdmObjectReference"
    $objReference.ObjectSid = $fullAccessUserSid
    
    # Set Send As delegates.
    $sendAs.Add("ADS_PROPERTY_APPEND", $objReference)
    
    # Set the Full Access permissions.
    $permission = New-Object "Softerra.Adaxes.Adsi.Exchange.AdmExchangeMailboxPermission"
    $permission.AllowedRights = "ADM_EXCHANGE_MAILBOX_RIGHTS_FULL_ACCESS"
    $permission.Trustee = $objReference
    
    $permissionModification = 
        New-Object "Softerra.Adaxes.Adsi.Exchange.AdmExchangeMailboxRightsModification"
    $permissionModification.Operation = "ADS_PROPERTY_APPEND"
    $permissionModification.Permission = $permission
    
    $mailboxRights.AddModification($permissionModification)
}

$mailboxParams.SendAs = $sendAs
$mailboxParams.MailboxRights = $mailboxRights

# Save changes
$Context.TargetObject.SetMailParameters($mailboxParams, "ADM_SET_EXCHANGE_PARAMS_FLAGS_NONE")