I just finished my Exchange migration from 2007 to 2013 I had some issues and still working through some, but I've never seen this before. On some mailboxes, exchange increased the storage limit on it's own. I don't know why or how, but this is a problem, because my mailbox database size doubled from 2007 to 2013. For example, on my own mailbox size, it was set to 5GB when in exchange 2007, but now, it's 35.15GB and I have never increased it to that amount.
I have attached a picture for clarification purposes. What do I do to make sure this doesn't happen again, and is there a powershell command I can run that shows me all users and their mailbox size limit, so I can go and reduce the size?
Dan