Auto Zip Attachments Extension for Thunderbird 3.0

One of the great extensions for Thunderbird is Auto Zip Attachments that enables the users to automatically compress attachments on-the-fly. However, the extension available at the Mozilla website is not compatible with the latest Thunderbird 3.0. Good thing I'm offering a modified version that'll work with TB3.

UPDATE: I have updated the extension to support the current version of Thunderbird (version 3.1).

What makes Thunderbird (TB) a kick-ass desktop mail client is its flexibility that makes it extensible through various addons/extensions and plugins.

One of my favorite extensions since TB1.5 was the Auto Zip Attachments, which automatically compresses (zip) attachments on-the-fly. This is especially useful for email messages sent with MS Excel or Word format attachments, wherein compression ratio are usually high. No more need to manually zip the files from the file explorer before attaching the same to email to save on bandwidth, which likewise translates to speedier file transfer.

Unfortunately, the developers of this extension appear to have forgotten about it and failed to update the same to keep it abreast of the new and more robust Thunderbird 3.0. It’s only compatible upto TB2.0. It seems that changing the max version in the install.rdf file is not enough. Instead, it involves editing further another file deep into the .xpi file, as described in one of the reviews for this extension.

Following the instructions from the reviews/comments on how to edit the .xpi file to make it compatible with TB3, I successfully installed the Auto Zip Attachments extension into my own TB install. I took the liberty to make that modified extension available here for everybody’s consumption. Download link below:

Auto Zip Attachments Extension for Thunderbird 3.1

Download and unzip the file, then install to your TB3 desktop client. Would appreciate feedbacks for any problems or issues encountered. Hope we enjoy Thunderbird 3.0 more with this extension.

No Comments

vinoi June 23, 2010 Reply

ayus part!!!

“no (manual) zip!)

deuts June 23, 2010 Reply

@vinoi, asteeg guid na ya basta Thunderbird part!

Laurent June 27, 2010 Reply

It doesn’t work with mac os 10.6.4 or I didn’t succeed to install in TB3

Have you a solution for mac ?

deuts July 6, 2010 Reply

Sorry Laurent, I don’t have a mac to try this on.

pink September 14, 2010 Reply

Automatic zipping while sending does not work 🙁

deuts September 21, 2010 Reply

Hi Pink, I hope you can elaborate what really was your problem, then I can try to replicate it in my system. Then, I can offer solutions if I could come up with one. Thanks!

Pink September 22, 2010 Reply

Hi Deuts,
I tried to post my settings and how to reproduce the problem, but I always end up with a white screen when I press the “send button” here.
Maybe you can tell me an e-mail-address where I can sent my comments to ?

deuts September 22, 2010 Reply

Hi Pink, it actually worked for me. I tried it in my system. I tried checking the option in the add-on to “Zip automatically when sending” and so far it worked. Maybe you can start by describing what OS you are using.

Pink September 22, 2010 Reply

I guess my comments are too long for this input box here.

Pink September 22, 2010 Reply

Hello Deuts,
I am using two computers:
one with Win XP and one with Win7.

AutoZip Options ==> Tab “Advanced”:
* Automatically Zip while sending –> YES
* Use user-defined settings –> YES
* Confirm automatic zipping –> YES

deuts September 23, 2010 Reply

Have you tried manually pressing the zip button in Thunderbird??

Pink September 23, 2010 Reply

Yes, manual zipping via the zip button works.

I also de-activated all other Add-Ons for testing. But didn’t solve the problem.

Thunderbird’s error console also doesn’t show any error concerning Auto Zip.

deuts September 23, 2010 Reply

Seriously, Pink, I don’t know how I can help you without actually sitting at your desk and do the troubleshooting. How about trying to create a new profile and install the same plugin in there. Or re-install thunderbird and delete your user profile for the previous install.

Pink September 24, 2010 Reply

Thanks for the tip.
With a new test profile, automatic zipping while sending works.
I am wondering what’s wrong with my default profiles (because I have the same problem on two different computers).
I will have to investigate…

Sorry for reporting a bug. Seems not to be one.

deuts September 24, 2010 Reply

That’s great! Enjoy the add-on! 😀

Pink September 24, 2010 Reply

Hi Deuts,
I found the reason why automatic zipping while sending doesn’t work in my case:

I set Thunderbird’s pref:
mailnews.sendInBackground –> TRUE

Maybe you can have a look at this ?
Thanks a lot 😉

deuts September 24, 2010 Reply

Yes that mailnews.sendInBackground is false in mine. Great that you actually found the culprit. At least it can be useful to other people who might find their way into this site. Thanks!

Pink September 24, 2010 Reply

Is there a chance for you to make AutoZip Attachments work with “Send in Background” ?

deuts September 24, 2010 Reply

Unfortunately, I’m not the developer of this addon, and I don’t have a background in programming. 😀

TrV December 30, 2011 Reply

I’ve found this site googling…

Here is an alternative to Auto Zip Attachments:”Auto Compress File”.

Everything has been completely rewritten from scratch, but the main idea was to provide a “modern” alternative to this former useful but obsolete addon.


I can garantuee better flexibility and maintenance (i am the developer!).

ACF works for MAC, and ACF works also for background sending !


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