Postbox BETA 7 Release




Oops! We have some issues with our fancy new migrator, so we're pulling BETA 7 until we can address these issues in BETA 8. Thanks in advance for your patience as we wrap up this next BETA release!

Hello, and welcome to the Postbox BETA program!


  • You must have a Postbox 5 license and be running one of these operating systems:
    • macOS 10.11 or higher
    • Windows 7, 8 or 10
  • You must be HIGHLY TECHNICAL, with an ability to troubleshoot issues on your own with no supervision
  • IMAP accounts only, absolutely no POP accounts at this time
  • Willing to use a product that is in very early development
  • Can file detailed bug reports, complete with steps to reproduce and other technical details

If this sounds like more than you bargained for, no problem, simply wait for the production version.

Important Changes in BETA 7!

Profile Migration

Postbox BETAs now install into new data folders, preserving compatibility for older releases. When you first start BETA 7, you will be presented with an option to migrate settings from earlier versions of Postbox.


Select "Postbox 3, 4, or 5" then select the profile that you created specifically for testing Postbox BETA releases (as instructed in previous release notes) and Postbox will migrate a subset of settings over.

The migrator will bring some, but not all, settings over from your previous install. Local mail data will be copied over, but mail data from IMAP servers will need to be re-downloaded. Additionally, you will need to reindex messages by navigating to Tools menu > Indexing > Index All Folders. As we progress through future BETA releases, we'll add more preferences to the migrator to make the switch to Postbox 7 as seamless as possible.


Postbox is based on Mozilla code, and as of Firefox Quantum, Mozilla has discontinued support for add-ons. As such, a decision has been made to remove add-ons functionality from Postbox at this time.

Postbox's Signatures and Responses add-ons have been rolled into the core product. Cloud File Sharing and installable Dictionaries will be supported in future BETA releases.

Add-ons from 3rd parties will no longer operate in Postbox, but we may opt to roll certain 3rd party add-on functionality into Postbox in the future.

Config Editor

The Config Editor has been removed from Postbox. Critical preferences that have traditionally been accessed via the Config Editor will be added to our profile migrator and to the Preferences UI over time.

Since Postbox 7 will install into new data folders, some of the preferences you may have set in the Config Editor will not currently migrate over. If this prohibits testing of the BETA 7, simply revert back to Postbox 5, then let us know what's wrong so that we can add these preferences to the Profile Migrator and Preferences UI.


The macOS and Windows themes are being updated, but please note that this is very much a work in progress. We're incorporating the feedback we've received since the release of Postbox 5, but there are still many tasks left to complete. The theme should be ready to review/feedback in BETA 8.

Special Installation Instructions for macOS

We're not currently signing BETA builds, so please follow these instructions in the short term:

  • Download the Postbox BETA and copy the application to your desired location.
  • Right-click the icon, and then select "Open" from the contextual menu.
  • Click "Open" when you see this dialog appear:


What to Look For

At this time we're looking to stabilize existing functionality found in the production version of Postbox.

Specifically, if something is not working in the BETA that is working in the production version of Postbox, then we'll want to know about it.

BETA Downloads:

  • macOS - please check back for our BETA 8 release
  • Windows - please check back for our BETA 8 release


Please let us know about any issues that you find on the Postbox BETA Feedback page. 

(While we appreciate each submission, and we receive thousands, please note that we cannot respond to the comments you submit.)


Thanks very much for helping us test this exciting new release!

- The Postbox Team