To ensure that your data is safe, we highly recommend backing up your Postbox data on a regular basis. There are excellent tools available for Mac and Windows users that will make backing up the Postbox profile easy, so that your messages and configuration are safe.
It is your responsibility to verify that your backup solution is properly backing up the Postbox data folder! The Postbox data folder can be found here:
(Note: In macOS the Library folder is hidden. To access it, open the Finder, hold the Option key, then select Library from the Go menu.)
Windows Vista, Windows 7
(Note: The AppData folder is folder is a hidden folder; to show hidden folders, open a Windows Explorer window and choose "Organize → Folder and Search Options → Folder Options → View (tab) → Show hidden files and folders".)
Users running macOS can use the built-in Time Machine utility to back up their system. By default, Time Machine will create hourly backups while the designated external hard drive is connected. Time Machine makes it easy to restore the Postbox profile to a specific date and time. Click here to read about Apple's Time Machine Utility.
Windows users may be interested in MozBackup, a free utility that allows users to create a backup of their Postbox profile. Click here to visit their website: MozBackup
KLS Mail Backup
In addition, KLS Mail Backup provides a more robust email backup solution, offering full and incremental backups, flexible restore options, and more. Visit their product page here: KLS Mail Backup
Postbox Backup (zebNet)
Finally, Postbox Backup from zebNet is another excellent backup solution designed specifically for Postbox users. Multiple profile backups is among the list of many powerful features. Check it out and download a free trial here: Postbox Backup
Savvy users may feel comfortable with manually backing up the Postbox profile. Although this method is less flexible than the tools listed above, it's useful for quick backups or moving a profile to another machine. Since the entire Postbox profile is self-contained, moving it to an external hard drive will accomplish a complete backup. Note: It is not recommended to dissect the Postbox profile to perform a selective backup.
Please refer to this article which describes where to find the Postbox profile: Postbox Profile Data