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Sync Apple Mail Between Macs Using ChronoSync Express

INTRODUCTION

This guide explains the steps necessary to create a set of ChronoSync Express Synchronizer Documents that can maintain Apple Mail messages in sync between two Macs.

AUDIENCE

This guide assumes that the reader is familiar with macOS, The Finder, and the hidden 'Library' folder located in the user home folder. This guide can touch on advanced topics and may not be suitable for beginning Mac users.

BEFORE GETTING STARTED

To sync Apple Mail between two Macs using ChronoSync Express, the following four conditions must be met, otherwise the practice described in this Guide will not work well.

  1. POP E-mail Account(s)

    There are two methods or protocols for controlling email: POP and IMAP. POP stands for "Post Office Protocol". POP downloads email messages from the Mail server to your device and is most often used when there is limited capacity on the Mail server.

    IMAP stands for "Internet Message Access Protocol". IMAP leaves messages on the Mail server so they can be accessed from any device. Email accounts like Gmail, iCloud, and Yahoo use IMAP because they store all of your messages on a remote server.

    Any e-mail accounts setup in Apple Mail must be POP-type accounts. You can check this by opening Apple Mail, launching Mail->Preferences, and visiting the Accounts tab. The 'Account Type' must be POP for all accounts.

    Keep in mind that if you are using IMAP e-mail, then it is best to continue with the IMAP as it will automatically synchronize email between Macs and other devices that connect to the IMAP account. Don't use ChronoSync Express to try to synchronize IMAP email accounts.

  2. Only Macs

    ChronoSync Express can only synchronize email between Macs. If syncing to other devices including phones or tablets is needed, then consider switching all mail to IMAP-type accounts.

  3. No Merging Apple Mail Data

    ChronoSync Express can keep email messages on two Macs in sync but it can not merge messages together from two different Macs. Most email programs store the email messages in database files. ChronoSync Express can replace the newer database file with the older database file, but not merge the two files together.

  4. Identical Versions of macOS and Apple Mail

    A Mail synchronization must only be done between identical versions of macOS and Apple Mail. For example, do not attempt to sync between Mountain Lion and Mavericks, and avoid syncing between different versions of the same OS, such as syncing between 10.10.1 and 10.10.2.

THE HOME FOLDER

macOS creates a home folder for each user account. These can be found by navigating to the root of the Startup Volume using Finder and opening the 'Users' folder. Your home folder should have a house icon rather than a folder next to it. Home folders are identified by the short name specified in the user account that created it. Note that the home folder used to appear by default on the Desktop and in Finder sidebars but Apple has taken steps in recent OS versions to make it less visible. Now it no longer appears in such places. If it does not appear in your Finder sidebar, we recommend you invoke Finder Preferences, select the "Sidebar" tab, and enable your home folder as a favorite. It will have the house icon with your short user name next to it.

The home folder of each user account contains documents, media, desktop items, preference settings, and other information. This keeps all of your personal files and information separate from other user accounts on the Mac.

Some information such as preferences, and application specific settings is kept in a hidden folder within the home folder called 'Library'. macOS has chosen to keep this hidden as the OS and application files are the only processes that should be modifying items in the 'Library'.

SETUP STEPS

Step 1: Install ChronoSync Express

Make sure you have ChronoSync Express installed on the Mac you use most or your 'primary' Mac.

Step 2: Locate the files in the Mail application

You don't actually sync the email application, you sync the email database which is located in 3 folders:

Mail Folder
The Mail folder is located under "Home/Library/Mail". (Apple Mail stores all its messages files in this folder.)

Mail Downloads Folder
The Mail Downloads folder is located under "Home/Library/Mail Downloads". (Apple Mail stores all its downloaded attachment files in this folder.)

Mail Preference File
The Mail Preference file is located under "Home/Library/Preferences". (Apple Mail stores all its preferences in the file: com.apple.mail.plist.)

Step 3: Get Mail Messages on One Mac

Make sure that all your email messages are on one Mac and then remove messages from the other Mac. To be safe, you can 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 4: Create Synchronizer Documents

You'll need to create and save the following 3 Synchronizer documents:

  • Synchronizer Document #1

    Create a Synchronizer document with the two "Mail" folders from each computer as the targets. Change "Operation" to Synchronize Bidirectional. Check "Synchronize deletions". Check "Archive replaced files".
  • Synchronizer Document #2

    Create a Synchronizer document with the two "Mail Downloads" folders from each computer as the targets. Change "Operation" to Synchronize Bidirectional. Check "Synchronize deletions". Check "Archive replaced files".
  • Synchronizer Document #3

    Create a Synchronizer document with the two "Preferences" folders from each computer as the targets. Important: For this particular document, be sure to create the "Simple" rule described below. Change "Operation" to Synchronize Bidirectional. Check "Synchronize deletions". Check "Archive replaced files".

Step 5. Create a Simple Rule

For the Preference folders only (synchronizer document #3 above), create the following simple rule: "Displayed Name: File or folder name contains: "apple.mail".

mail rule setup

Step 6. Create the Container document

Once the sync documents containing the folders from above have been created, they can be added to a container document. A Container is a document that contains multiple ChronoSync Express sync documents. A container document allows you to control several sync documents as if they were one document. Running a synchronization on a container will execute each contained document in the order it is listed. Choose 'Create a new container document' from the Document Organizer, or 'File -> New -> Container' from the menubar to create a new container. You can add the sync documents to the container by simply dragging them in and out or by selecting "Add..." or "Remove" from the toolbar.

Step 7. Run the synchronization

Once all the above-mentioned settings are in place, run the synchronization by choosing "Synchronize" on the toolbar in the Container document.

WATCH FOR THE FOLLOWING TYPES OF ISSUES:

Conflicts

Make sure to always synchronize each time you switch working to the other Mac. If you fail to do this, conflicts may arise. A conflict is when the same file has changed on both computers. Since you have to choose between one file or the other, you would lose the changes made to one of the files. If a conflict does arise, then choose the file from the computer you last used.

Scheduling

Since you need to synchronize every time you switch Macs, it is not practical to schedule your Mail Sync Container document. Instead, you should manually run the sync every time you switch Macs to ensure the two Macs always stay in sync. Doing this will take some getting used to, but it's a habit that should be practiced.

Errors or Problems

If you encounter any errors or have any problems you can contact us by using our support form.

3 Things to Remember

Since this is a bi-directional sync designed to keep files and folders in sync between two Macs, you should pay attention to your workflow.

  1. Make sure to always synchronize each time you switch working to the other computer.
  2. Always run every sync from the source Mac using the same Container document.
  3. If a conflict should arise, choose the file from the computer you last used.

Working on two Macs simultaneously can result in unusually high numbers of Conflict errors being reported and there may be difficulty merging the changes that can occur to the same files on both Macs. Instead, consider this workflow:

To switch from Left to Right Mac:

  • Using Left Mac.
  • Run Sync from Left Mac (The ChronoSync Express Mac).
  • Choose "Left Files" for any conflicts.
  • Begin using Right Mac.

To switch from Right to Left Mac:

  • Using Right Mac.
  • Run Sync from Left Mac (The ChronoSync Express Mac).
  • Choose "Right Files" for any conflicts.
  • Begin using Left Mac.

If you have any problems while using our products or have any questions about this guide, contact us by using our support form.