Hi,
From ESM there is no accurate way to measure the size of the store, adding up all mailbox sizes etc does not give you an accurate reading (this is alos applicable to isinteg and eseutil).
The reason this is not accurate is thaht using ESM / eseutil /ms etc.. they do not take into account the converion overhead of different formats, there are hidden tables and just generally hidden overhead (plus SIS is also not included).
Mark