Why convert MSG to OST?
An .msg file holds one saved Outlook email in Microsoft's Compound File Binary format. An .ost file is a database that Outlook creates automatically when connecting to an Exchange or Microsoft 365 account, caching the entire mailbox for offline use. The OST is synchronized against a live server and tied to a specific account and profile; no converter writes to it because the task has no defined outcome.
How to convert MSG to OST
Microsoft Outlook APP
Drag the .msg file into any open Outlook folder to import the item into your mailbox; Outlook adds it to the OST automatically as part of normal sync.
Mozilla Thunderbird FREE
Import the .msg using the ImportExportTools NG add-on and convert to .eml as a portable alternative that opens in any mail client.
Programs that convert MSG
About these formats
.MSG
Outlook Message (Microsoft Outlook saved email)
An MSG file is one email - with subject, sender, recipients, body, and any attachments - saved from Microsoft Outlook in Outlook's proprietary binary format. On Windows, double-click it in…
Open .MSG details →
.OST
Outlook Offline Storage Table
An OST file is the local offline cache Microsoft Outlook keeps for an Exchange, Microsoft 365, or IMAP account - a copy of your mailbox so Outlook works without internet. You don't open it…
Open .OST details →Quality & what to watch
- OST files are tied to a specific Outlook profile and Exchange account; no converter writes to them independently.
- The only way to add a
.msgto an Outlook data store is to drag it into an open Outlook folder, which imports the item normally. - Sites claiming MSG-to-OST conversion typically rename the file without changing its content or produce unrelated output.
Frequently asked questions
Why do some sites claim to offer MSG to OST conversion?
How do I add a saved .msg file to my Outlook inbox?
.msg file into any folder in open Outlook - it imports the item and Outlook syncs it to the OST automatically.
