Postbox automatically excludes IMAP folders from Time Machine backups for the Mac user accounts with Administrator privileges to decrease the size of your backup. If you are using a Standard or Managed account, follow the instructions below to manually exclude ImapMail folder from being backed up on Time Machine.
Exclude Certain Postbox Files from Time Machine Backups
Postbox's mail format is one-file-per-folder (also known as the "mbox" format) which can result in very large Time Machine backups.
To solve this problem, you can exclude the ImapMail folder from being backed up on Time Machine as this information is already backed up on the server.
The ImapMail folder can be found in your Postbox profile folder.
To exclude files and folders from Time Machine:
- Open System Preferences, click on the Time Machine icon.
- Click on the "Options..." button
- Click on the [+] button to add files and folders to be excluded
To exclude the entire Postbox data folder, select "PostboxApp."