How to Read Postbox File Format

View Postbox Email

postbox mail

Introduction of Postbox Mail client

We all received number of emails every day. Most of us actually spend a significant part of the day working with mail. The mail client is probably the most used application after your web browser, assuming you don't use the web for your mail. I use the default mail app on Mac OSX – – and I am little bit surprised to realize I have not actually explored my alternatives.

I have been using, I think, from the day I moved my client-side platform to the Mac. It seems like a valid choice, as it came free with Mac OS X, and Apple was supposed to be good at making amazing applications. I just expected that was the mail client everyone on the Mac should use.

After working with, finally I decided to check out the alternatives. Particularly, I was searching for something which could handle Gmail email well, and more specifically, Gmail handling of labels. If you use Gmail and an IMAP client, you will get to know there are some typical complications because Gmail uses IMAP folders to represent their concept of labels. It is because IMAP does not have a concept of labels. (Actually they do, called keywords, but somehow Google did not want to make use of IMAP keywords.)

The first alternative I checked out was Sparrow. It was so amazing and handles Gmail labels very nicely. Moreover, it had been observed by Google and the development of Sparrow has been stopped.

Next, I switched to another alternative i.e. Airmail Beta. It handles Gmail labels very well too. Mails that are labelled multiple times are still signified in Airmail as a single message, and not with duplicate copies.

Lastly, I came across with Postbox which is a very solid application. Apparently, it has been around only for some time, and supports both Windows and Mac OS. It does just about everything you need an IMAP mail client to do. Also, it understands Gmail labels, and that a single message can have many labels. Alas, Postbox create the duplicate copy of the message for every label. This email application supports IMAP keywords, in case you are interested, even though Gmail would not map that to labels.

Postbox is about as feature complete as I could ever want in an IMAP email account. It does handle local folders (i.e. mail on the local computer as compared to a remote server), something that both Sparrow and Airmail Beta does.

The all three email application pretty much be used and controlled completely by keyboard. Sparrow is a pretty much dead end now as they have paused the development. And the other one i.e. Airmail Beta looks pretty and promising, but still it has few ways to go in terms of feature set.


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How the mail clients store mail internally?

Airmail make use of a set of SQLite databases for each email account. On the other hand, Postbox use MBOX format on a per-folder basis which means each folders get stored in .mbox format, supplemented by some index files. Basically, whenever a small little thing changes in one email, then entire MBOX file or SQLite database changes.

Impact: The time machine backups are always going to have loads of data to backup. For example, if in case that Airmail Beta email account that currently has a 5GB database receives one new email, that 5GB database changes, and the Time Machine will have to backup 5GB worth of files. This means, in a practical sense, you need to possibly exclude Airmail and Postbox data folders from Time Machine Backup. (Technically it is OK to not backup your IMAP data since your IMAP server already has a copy anyway.)

How to export Postbox Mail to other email application?

After switching in Postbox, I have realized that it does not handle Gmail labels as efficiently as Airmail Beta. Neither did anyway. What is important is that Postbox let to use my keyboard, includes number of functionalities and I haven't missed anything from Airmail Beta, currently, is not able to move email across accounts. It is something that I need, and I have submitted a feature request to the Airmail Beta team and I hope they will get this done soon.

Now Postbox email application is not in use by users as there are number of advance email applications coming up with improved functionality. And there are many users who make use of Windows OS instead of Mac OS X. And sometimes sudden situation occurred where users are unable to open Postbox files on Windows version. There are plethora of reasons behind such issues. Due to this users start looking for a solution that can allow to view Postbox files in different email application.

Steps to export Postbox Mail in other email application

In order to perform the required task precisely, number of third party utilities are available which will quickly accomplish the task by clicking on few simple steps:

  • Directly launch the application on your system
  • Browse the path and select the required Postbox files you want to read
  • After successful completion of the task, now you can easily open Postbox file format in the desired format.


In the above section I have described about different mail application alternatives and how to open Postbox files in other email application format. Implement the steps and you will surely achieve the task you were searching for.