ChronoSync can keep email messages on two Macs in sync but it can not merge the messages together. What's the difference? First you need to understand that most email programs store the email messages in database files. ChronoSync can replace the newer database file with the older database file but not merge the two files together. So, if you have received new email messages on both Macs in between synchronizations, ChronoSync can not combine all the messages so they all exist on both Macs. In such an instance, ChronoSync can raise a conflict between the two email database files, but it will be up to you to decide which one should be used.

In order to use ChronoSync to synchronize email clients you must first make sure all the messages you want are on at least one Mac. Then, you need to perform a one-time forced synchronization (as mentioned in Step 5) and copy the messages to the other Mac. After doing so, both of your email clients will contain identical messages. From this point on you should discipline yourself to always synchronize before you use the other Mac to receive email, or else you could end up with new messages on both Macs again.

You can only perform a Mail synchronization between the same version of Mac OS X, meaning you must sync Tiger to Tiger but not Tiger to Leopard. Furthermore, you need to make sure that your Mail applications are the same version. However, you can synchronize certain files, like document files, between any OS that your Mac can copy to. For instance, you can synchronize your Documents between Tiger and Leopard or even Tiger and Windows XP. If you are unsure if you can synchronize a particular scenario, ask us by filling out our support form describing your situation .

Step 1. Locate

Locate the email database.
Note: You don't actually sync the email application, you sync the email database.

Step 2. Defining the Source Mac

When synchronizing, you need to establish a source and destination. The source is the Mac where ChronoSync is installed and the destination is the Mac you connect/mount. You can make either one the Left or Right Target. Once you establish your source Mac you need to make sure that all your email messages are on that Mac. How? Simply email any missing messages to yourself and receive them on the source.

Step 3. Connect

You only install ChronoSync on one Mac and then connect to the other. You need to, of course, connect to another Mac in order to synchronize to the other Mail folder. Click here for a list of connection options.

Step 4. Set It Up

Create a ChronoSync document with the two "Mail" folders from each computer as the targets.
Change the Operation to "Synchronize Bidirectional".

Check the Synchronize Deletions checkbox, as it is best to archive files when deleting. If you want to archive all files when they change, then turn on Archive Handling from the Options Panel.
Save the ChronoSync document and always sync when switching Macs and always run the same ChronoSync document.

Step 5. Remove Messages

Make sure you completed Step #2 and all your messages are on the source Mac. Now, empty the contents of the Mail folder on the destination Mac. You can simply drag everything into a temporary folder on your Desktop. This will ensure that everything from the source Mac will copy over to the destination Mac and be completely identical to start with. After you verify that Mail is working on both Macs you can trash the temporary folder.

Step 6. Preference File

There is one Mail preference file that also must be synchronized between both Macs. Find the file "com.apple.mail.plist", located under Users/HOME/Library/Preferences.

There is one Entourage preference file that also must be synchronized between both Macs. Find the file "com.microsoft.Entourage.plist", located under Users/Home/Library/Preferences

If you are synchronizing your entire HOME folder, including Preferences, then you are set. If not then you need to sync this file over too. You can set up a separate sync document synchronizing your two Preference files with a Simple Rule - "Displayed Name: File or folder name is: com.apple.mail.plist" (if synchronizing Apple Mail).