Apple Mail and Outlook perform the task of managing your email in a similar manner. However, the file formats used to store your contacts and messages in the two programs differ considerably. The Mac mail program does not offer native support for importing Outlook PST files into Apple Mail directly, but several commercial apps are available for this purpose. If you want to import your Outlook contacts and messages into Apple Mail without having to purchase an expensive third-party app, you can use the free Thunderbird email client as a go-between for the mail programs.

Prepare USB Flash Drive or External Hard Drive

Step 1

Connect the USB flash drive or external hard drive to the Windows computer. If an AutoPlay window opens, close it.

Step 2

Press "Windows-E" to open File Explorer, and then select "Computer" in the navigation pane.

Step 3

Right-click the drive letter of the USB flash drive or external hard drive in the "Devices with Removable Storage" section. Click "Format" on the pop-up list.

Step 4

Click the "File System" drop-down list and select "FAT32." Click the "Start" button and wait a few minutes for Windows to format the drive with the FAT32 file system.

Import Outlook PST File Into Thunderbird

Step 1

Open a new browser tab or window. Navigate to the Mozilla.org website, download the latest version of Thunderbird and install it on the Windows machine (link in Resources).

Step 2

Close Outlook if you have not already done so. Launch Thunderbird on the Windows computer. Click "Tools" on the menu bar and select "Import." Select the "Import Everything" option and click "Next."

Step 3

Highlight "Outlook" in the program list and click "Next." Wait a few seconds for Thunderbird to scan the system for the Outlook PST file and then import it. Click the "Finish" button when prompted.

Export Thunderbird File to Apple Mail

Step 1

Open File Explorer on the Windows computer. Navigate to the "C:\Users\yourusername\AppData\Roaming\Thunderbird\Profiles\profilename.default\Mail" folder where "yourusername" is your Windows account name and "profilename.default" is the username created in Thunderbird.

Step 2

Select all of the files in the "Mail" subfolder, and then press the "Ctrl-C" to copy them to the Windows clipboard.

Step 3

Click the drive letter of the USB flash drive or external hard drive in the navigation pane. Press "Ctrl-V" to copy the Thunderbird profile files to that drive.

Step 4

Disconnect the USB flash drive or external hard drive from the Windows computer, and connect it to the Mac machine. Wait a few seconds for OS X to detect the drive and automatically mount it.

Step 5

Launch Apple Mail. Click "File" on the menu bar and select "Import Mailboxes" in the drop-down list. Select the "Thunderbird" option in the Import window and click "Continue."

Step 6

Click the device name of the USB flash drive or external hard drive in the Devices list of the Finder window. Select all of the profile files on the USB or external drive, and then click "Choose."

Step 7

Verify that all of the files in the Import window have check marks next to them and click "Continue." Wait a few minutes for Apple Mail to import the contacts, messages and other items from the Thunderbird profile. After the import process finishes, you can view all of the items in Apple Mail.