Postbox
I don’t work for Postbox, but I do appreciate their software and how it actually does what I want. This is why I am promoting it to friends and family alike.
This guide is written for Postbox 1.1.1, on Mac OS X (I’m on 10.6.2 at time of writing this), so I cannot guarantee success on the Windows version via the same steps, but all the settings in Gmail + preferences should be more or less identical.
When you get this set up, you should be able to archive messages just like in the web interface to keep on the Gmail servers, delete emails to the trash (or immediately) via Postbox, and get the most out of your Gmail-on-desktop experience. I hope this also helps anyone else who has trouble getting these things to work. I spent a good hour last night figuring it out.
If you read through this and try it out on a trial version, and you like what you see, you can save $10 on the purchase of Postbox by using a referral purchase page here (you will see a small message at the top confirming the $10 discount). Students with valid photo ID will get a 50% discount too.
So this application was mentioned by Lifehacker and I have since purchased it. I do not often purchase software (opting for the awesome freewares that are offered out there instead), but after using a trial version of this app, I instantly fell in love with the level of actual, real interoperability with Gmail IMAP. Having had no success with Mail or Thunderbird working properly with IMAP (i.e. archiving is wonky, as is expunging from the inbox), I tested this alternative out and found it to do exactly what I needed (mostly without any major configuration in the newer version).
If you’re looking for a feature list, please see their site for their marketing pitch.
I’m going to go over a quick guide to set up Postbox with Gmail, such that the archiving works along with trashing, inbox cleaning, and all that jazz. Currently, I have not found any other comprehensive guide that is proven to work that takes into account both the Gmail settings and the Postbox settings to ensure things play nice. Enjoy, and I hope this helps you if you’re having trouble.
Getting Postbox
First, you’ll need to go download a copy of Postbox (free trials are available for both Windows and Max OS X). Install by following the instructions (duh, straightforward, really). Go here for the download file (you’ll need to click the button at the top to get your OS-specific download, as their site automatically detects your operating system). Continue reading

