Why does mailbox size increase by 30-40% when moved to Exchange 2013/2016?

We get this question very often and its answer is right on the Exchange’s release notes “Mailbox size increase when migrating from previous Exchange versions”.  However, I wanted to provide a little more detail along with good resources already on the web. In Exchange 2013/2016 the mailbox size calculation, includes space that was not accounted for before, but effectively was part of messaging…

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Not all 106 are created equal

Of course that’s not accurate. When MSExchange Common source writes an event 106 about performance counters, the format of each event is exactly the same and reads: ID:       106 Level:    Error Source: MSExchange Common Machine:  server1.contoso.com Message:  Performance counter updating error. Counter name is <counter name here>, category name is <category name here>. Optional code:…

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