Shared PST Folder

Question

Shared PST Folder

TCATHF 215

Hi

I have Outlook 365 running on two PCs with a PST file on each for storing selected emails locally on the PC.

I have both PCs connected to Synology NAS to share common folders, like Documents, Downloads, Photos.

Can I locate a PST folder on NAS to share it between the two PCs, and can you have both PCs running Outlook 365 at the same time.

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Answer accepted by question author

simo-k 96,055 Volunteer Moderator

＞ My Outlook 365 is Microsoft Exchange.
What is the official subscription name you have?
Does it include an Exchange Online license for organizations?
(The Online Archive feature is for organizations, not for personal use.)
If you want to back up for personal use, you will need to use a PST file.
However, sharing a PST file with other PCs will cause file corruption.

<Japanese>
あなたが保有している正式なサブスクリプション名は何ですか？
組織向けExchange Onlineのライセンスが含まれていますか？
（オンラインアーカイブの機能は組織向けです。個人向けの機能ではありません。）
個人向けでバックアップする場合は、PSTファイルを利用することになりますが、PSTファイルを他PCと共有するとファイル破損します。

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2 additional answers

Your answer

Answer 1

Using a PST file stored on a NAS (Network Attached Storage) is not recommended for several reasons. PST files are not intended for long-term, continuous use in an enterprise environment, and sharing them over a network can lead to performance issues and data corruption. Specifically, while it is technically possible to specify a network directory for a PST file, Microsoft advises against this practice.

Additionally, having both PCs running Outlook 365 at the same time with the same PST file can cause conflicts and potential data loss. The supported scenario for networked PST files is limited and primarily involves using Microsoft Outlook 2010 or later on a Remote Desktop Session Host (RDSH).

For better management and performance, consider using alternatives such as Microsoft 365 Exchange Online or configuring Outlook in Cached Exchange Mode, which allows for local caching of mailbox data without the risks associated with shared PST files.

Answer 2

Francisco Montilla 30,725 Independent Advisor

Hello,

Do not do this. Outlook PST files must live on a local fixed drive. Placing a PST on a NAS or any network share is unsupported and commonly causes corruption and file locking problems. Outlook also cannot have two computers open the same PST at the same time. You can run Outlook on both PCs concurrently, but not against one shared PST.

The supported way to share archived mail between both PCs is to use an Exchange Online Archive mailbox so the data stays on the server.

If your mailbox is in Microsoft 365 Exchange Online, have your admin enable the Archive mailbox for your user, then restart Outlook on each PC and you will see Online Archive under your mailbox. Move the selected emails into that Online Archive or apply retention to move them automatically. Both PCs can stay open at the same time and see the same archived mail with no PST involved.

If you are not on Exchange Online, tell me what mail account type you use and I will guide you to the next path.

TCATHF 215 Reputation points

2025-12-25T22:27:14.6366667+00:00

Hi

Thanks for the information.

My Outlook 365 is Microsoft Exchange. How do I set up the Online Archive and does it archive my GMail folders, and all my local folders in the PST file.
Francisco Montilla 30,725 Reputation points Independent Advisor

2025-12-26T23:05:50.78+00:00
Because your account is Microsoft Exchange, the path is to enable your Exchange Online Archive and then move any mail you want to keep into it.

If you are the Microsoft 365 admin do this in the Exchange admin center. Sign in to admin.microsoft.com with an account that has Exchange admin rights. Open the Exchange admin center, go to Recipients > Mailboxes, select your user. In the Archive mailbox section choose Enable. Wait a few minutes, then restart Outlook on each PC. In the folder list you will see Online Archive - Your Name under your Exchange mailbox.

About Gmail and your local PST: The Online Archive is part of your Exchange mailbox only. It does not automatically capture Gmail folders or a local PST. You have two easy ways to bring that mail into the Online Archive using Outlook on one PC, the changes will appear on the other PC as well.

To import a PST straight into the archive use Outlook on Windows. In Outlook choose File > Open & Export > Import/Export. Pick Import from another program or file > Outlook Data File (.pst), browse to your PST and choose Replace duplicates with items imported or Do not import duplicates as you prefer. When Outlook asks where to put the data expand Online Archive - Your Name and pick the destination folder or the root. Check Include subfolders. Finish and leave Outlook open until the status shows All folders are up to date. After the import completes you can close or remove the PST from Outlook.

To move mail from Gmail in Outlook use the folder list. Expand your Gmail account. Create matching folders inside Online Archive if you want the same structure. Drag messages or folders from Gmail to the Online Archive. A move removes the items from Gmail once synced. If you need to keep a copy in Gmail use Copy instead of Move.

Once the archive is enabled and populated you can keep using both PCs at the same time. Outlook will open the same Online Archive from Exchange so there is no PST to share or risk of corruption.