How to import Outlook emails into Gmail, Thunderbird or Apple Mail
Gmail, Thunderbird and Apple Mail can't open .ost or .pst files. The way through is to convert the mailbox to MBOX, the standard format of those apps, and import it.
Create the MBOX
Choose MBOX
Open the .ost or .pst in the converter, go to Convert, choose MBOX and click Create MBOX.
Save and unzip the file
Each mailbox folder becomes one .mbox file. Subfolders go in folders with the same name.
Import into Thunderbird
Install the add-on
In Thunderbird, open Add-ons and Themes, search for ImportExportTools NG and click Add to Thunderbird. It is free.
Import the .mbox files
Right-click Local Folders and choose ImportExportTools NG, Import mbox file. Select the files from the unzipped folder.
Move it to Gmail
Add your Gmail account to Thunderbird
Use File, New, Existing Email Account and sign in with Gmail. Thunderbird sets it up on its own.
Drag the folders
Drag the imported folders from Local Folders to the Gmail account. Messages upload with date, sender and attachments, and show up in Gmail as labels.
Large mailboxes take a while to upload: keep Thunderbird open until it finishes. The space used counts toward your Google storage.
In Apple Mail (Mac)
Import the mailboxes
In Mail, use File, Import Mailboxes, choose Files in mbox format and select the unzipped folder. The folders show up under On My Mac; drag them to iCloud or another account if you like.
Common questions
- Do attachments come along? Yes. Every message goes complete, with attachments, images and attached messages.
- What about contacts and calendar? They are not part of MBOX. Use the Contacts and calendar format: see Outlook contacts and calendar to your phone.
- I use Google Workspace on Windows. Google's tool for Outlook (GWMMO) imports .pst files directly: convert the .ost to PST and use that tool.
Read your file now, for free. Open the .ost in your browser, check folders and messages, and convert it to PST. The file never leaves your computer.
Open the converter