Links para resolução:

https://support.microsoft.com/pt-br/help/982577/the-file-size-limits-of-.pst-and-.ost-files-are-larger-in-outlook-2010-and-outlook-2013

https://support.microsoft.com/pt-br/help/832925/how-to-configure-the-size-limit-for-both-.pst-and-.ost-files-in-outlook