• Download the Add-on to your computer, such as the Desktop.
  • In Postbox, go to the Tools menu and select Add-ons.
  • Click the Gear icon or button in the upper right corner, then select Install Add-on From File...
  • Browse to the location of the add-on and select it.
  • Restart Postbox.

Trouble-Shooting and Support

Add-ons can change the DNA of Postbox in ways that are incompatible with its default behavior. If Postbox is not operating the way you expect, our recommendation is to temporarily disable add-ons to see if the problem clears up for you.

Postbox does not support the functionality of 3rd party add-ons, as it is up to each developer to support the functionality of the add-ons they author. If an add-on is not working correctly, please contact the add-on developer directly.

Postbox Add-ons

70 Email Templates Every Business NeedsPostbox, Inc.70 professionally written email responses that anyone can customize and use. You'll receive emails for finding a job, hiring, making introductions, reaching out to investors, sales, and more. Only available for Postbox 5Download  |  Instructions
25 Professionally Designed Email SignaturesPostbox, Inc.25 professionally designed email signatures that will present you in the best light possible. Each signature is fully customizable, and contains all the code examples you need to make a lasting impression. Only available for Postbox 5Download  |  Instructions
Cloud File Sharing Add-on 1.0.1Postbox, Inc.Share links to your Dropbox, Box, and OneDrive files instead of mailing the files themselves. Only available for Postbox 4 and 5.Download  |  Instructions
Vacuum Postbox 1.1Postbox, Inc.Adds a "Tools | Indexing | Vacuum..." menu item which allows you to vacuum your Postbox index to reclaim disk space and improve performance.Download

3rd Party Add-ons

Markdown HereAdam PritchardMarkdown Here allows you to write complex email in simple text, never taking your hands off the keyboard.Download
SpamSieveC-Command SoftwareIntegrate Postbox with SpamSieve's powerful junk filtering on macOS.Download for macOS
ImportExportToolskaosmosImport and Export Messages.Download
Enigmail 1.2The Enigmail TeamSend and receive signed and encrypted messages using OpenPGP provided by GnuPG. You also need to install GnuPG.macOS  |  Windows
MinimizeToTray RevivedNils MaierMinimizes Postbox to the system tray on Windows.Download
Send LaterJonathan KamensTrue "Send Later" functionality to schedule the time for sending an email.Download
MailHopsAndrew Van Tassel MailHops maps the route an email took to get to you.Download

Developer Resources

Here are a few resources that you may find helpful to your porting efforts: