How to Import OST File to Gmail
In short: To import OST file to Gmail, remember there is no direct route. The usual GWMMO tool works only with Google Workspace, not a free @gmail.com. For personal Gmail, add the account to Outlook over IMAP with an app password, then drag the OST folders into it so they upload. A converter can also send an OST straight to Gmail, including orphaned files, with no Outlook needed.
Why there is no direct OST to Gmail import
Knowing this saves you from a dead end. An OST is an Outlook offline cache that Gmail has no button to read. The old advice is to convert the OST to a PST and push it up with GWMMO, the Google Workspace Migration for Microsoft Outlook tool. The catch that most guides skip is that GWMMO only works with a paid Google Workspace account. On a normal free @gmail.com it will not sign in, so those steps lead nowhere. What actually works depends on your account: Workspace users can use GWMMO, while personal Gmail users move the mail over IMAP instead. Either kind can use a tool.
Technical Executive and Staff Writer, Corbett Software
“People burn an hour on GWMMO before realizing it never accepts a free Gmail, because it is a Workspace tool. If you are on a normal Gmail, add it to Outlook over IMAP and drag the mail across. For an orphaned OST with no Outlook, a converter sends it to Gmail directly.”
Google Workspace: the GWMMO route
If your Gmail is part of a paid Google Workspace, GWMMO is the free official path.
- In classic Outlook, go to File, then Open & Export, then Import/Export, then export the OST folders to a PST.
- Download GWMMO from Google and sign in with your Workspace address.
- Choose From a PST file, select the PST, pick the data, then start the migration.
This only works for Workspace. If sign-in is refused, your account is a normal Gmail, so use the IMAP route below.
Personal Gmail: add it to Outlook over IMAP
For a free @gmail.com, the reliable free route is to let Outlook do the upload over IMAP.
- Turn on 2-step verification on your Google account, then create an app password for mail.
- In Outlook, go to File, then Add Account, add your Gmail address, then use the app password if asked.
- With both the OST account and Gmail open in Outlook, select the OST folders or messages you want.
- Drag them into a folder under the Gmail account. Outlook uploads them, so they appear in Gmail online.
You can make a new Gmail label first, then drag into it, to keep the imported mail together.
Send an OST straight to Gmail with a tool
When the OST is orphaned or you have no Outlook, a converter reads the file and uploads it to Gmail for you.
The Corbett OST Converter reads an OST directly, with no Outlook, then exports it to Gmail over IMAP with an app password, keeping folders and attachments. It handles orphaned and corrupted OST files, so a filter lets you upload only a date range or folder. A free demo edition lets you preview the mail first and runs on every edition of Windows.
- Install and open the tool, click Open, choose Email Data Files, then OST Files, then select your OST.
- Preview the folders, then click Export and choose Gmail or IMAP.
- Enter your Gmail address and app password, apply any filter, then Save.
Frequently asked questions
Can I import an OST file to Gmail directly?
No. Gmail cannot read an OST. Workspace users push a PST up with GWMMO, personal Gmail users drag the mail in through Outlook over IMAP. A tool can also send the OST to Gmail directly.
Why does GWMMO not work with my Gmail?
Because GWMMO only supports paid Google Workspace accounts. A free @gmail.com cannot sign in, so use the IMAP drag method or a converter instead.
How do I import an OST to a free Gmail account?
Add your Gmail to Outlook over IMAP with an app password, then drag the OST folders into the Gmail account in Outlook. The mail uploads and appears in Gmail online.
Do I need an app password?
Yes for a personal Gmail. Turn on 2-step verification and create an app password, then use it when Outlook or the tool asks for your Gmail password.
Can I import an orphaned OST to Gmail?
Yes, with a converter. It reads an orphaned or corrupted OST without Outlook and uploads it to Gmail over IMAP, so a broken account is not a blocker.
Will importing change my OST file?
No. Dragging in Outlook or running a converter only reads the OST. The original file stays as it is, so the mail is copied into Gmail.