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We have a problem with very large OST files of outlook. What we do is archiving the mails from the Exchange Server with a 3rd party software and delete them from the Exchange server afterwards.

Nonetheless the OST file size stays the same.

Do I really need to put the server in Maintenence mode (I have a technet article that details that over like 20 steps, or is there a faster method to accomblish that task?

Lian
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  • Depends on how you delete the mails from Exchange. Through OWA? Outlook? "3rd party tool"? – Lenniey Jan 17 '19 at 16:12
  • @Lenniey MailStore, the documentation states it deletes mails from exchange, if configured that way. But MailStore support says, the mails are marked for deleting in exchange and are only deleted after the exchange-maintenance procedure. MailsStore connects directly to the server, it has no direct interaction with Outlook and its local files – Lian Jan 18 '19 at 07:41

2 Answers2

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Nonetheless the OST file size stays the same.

This has nothing to do with the Exchange mailbox database. You need to compact the OST file in Outlook.

joeqwerty
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  • Or, delete them and let Outlook generate new ones. Radical, but sometimes the better path (especially for truly huge OST file sizes) – Ruscal Jan 17 '19 at 21:37
  • So the OST is not synchronized to the exchange profil, at least not regarding deleted elements? – Lian Jan 18 '19 at 07:43
  • It is, but the OST file size is not dynamic. If email has been deleted and you want to reduce the size of the OST file then you need to compact it. – joeqwerty Jan 18 '19 at 13:13
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Do you want to reduce the ost file size?

OST file is a cache of the mailbox data, as others said, you could simple delete or rename the ost file on client side, do a mailbox cleanup, and it would regenerate a new ost file while the next startup.

Also you could change to Outlook Online Mode if you don’t want a ost file.

By default, when a user soft deletes an item (accomplished by pressing the SHIFT and DELETE keys) or deletes an item from the Deleted Items folder, the message is moved to the “Recoverable Items” folder, thereby disappearing from the user’s view. I suggest you have a backup before delete them.

Shaw
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