Exchange server 2016 archive mailbox export PST size showing 3 times of archive mailbox size

Nagarajan K 96 Reputation points
2021-03-06T07:31:03.81+00:00

Dear Team,

We have exported the Exchange server 2016 archive mailbox PST. The PST size is showing 3 times huge on archive mailbox size.

Checked deleted item also but unable to find why PST is taking too much size.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Yuki Sun-MSFT 40,646 Reputation points
    2021-03-08T04:08:40.27+00:00

    Hi anonymous user,

    Based on my experience, it's common for the exported PST file to be much larger than the mailbox size. This is because Exchange Server mailboxes store email more efficiently than Outlook uses in a *.pst or *.ost.

    For more information, hopefully you can find the following article helpful:
    Comparing Mailbox and PST File Size

    By the way, I've seen several similar threads which also mentioned that the PST size is around 3 times huge on archive mailbox size, I'll leave the links below for your reference:
    Online Archiving into PST took too much space
    his online archive mailbox size is 48 GB but while I go to downloading his mailbox into .pst, it's .pst is more than 150 GB
    Mailbox size much smaller than PST size
    For those that still run their own Exchange, I usually see an average of 2-3x the size of PST vs actual mailbox in a stand alone user
    (Please Note: Since some of the web sites above are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.)


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