Thank you very much for the information.
We believe we have fixed the problem. The issue was that our code only looked for the first Message Store under each Storage Group. However, now we loop through each Message Store.
Can you please test out our patch. I have uploaded it here:
This is not public yet - but if you report that it works, then we will put these changes into the next build.
Incidentally, we found that people with multiple storage groups and mailbox stores may run into this problem if their backup user isn't part of the domain:
"The user granted 'Associated external account' right must also be granted 'Full mailbox access' right."
We believe this problem can be solved using this method:
http://forums.msexchange.org/m_18004101 ... 1800410181
This seems to happen when mailboxes are upgraded from Exchange 5.5.
Thank you for your patience, and please let me know how you go.