How to Make Incompatible Thunderbird Addons Compatible

Despite new features and potential performance gains, every major update from Mozilla’s Thunderbird is almost certain that some addons will be disabled due to version incompatibility.  It is very frustrating especially when some of these addons are key to one’s system.

Here’s how to quickly make incompatible addons compatible:

1. Locate extensions folder under the Profile folder of Thunderbird

2. Rename the file-extension of the addon to be modified from xpi to zip

3. Unzip the file and look for “install.rdf” inside the unzipped folder

4. Open the file with a text editor and edit the number of <em:maxVersion> to Thunderbird’s current version or higher

5. Save the file and then zip the whole folder

6. Rename the file-extension back to xpi from zip

7. The addon will now be compatible to the new version of Thunderbird

•   Although the addon can be used now, there may still be a chance of features incompatibility.
•   Same principle applies to make incompatible Firefox addon compatible.
• Location of Firefox Extensions is:
\Users\<user>\Library\Application Support\Firefox\Profiles\uzc25jg1.default\extensions


How to Sync Thunderbird Mails across Mac and PC

One of the beauties of Thunderbird is its mail data are both Mac and PC compatible.  One can simply copy the mail data from one platform to the other and then open it without any problem.

Like many others, my desktop is a Win-7 based PC and my portable is a Mac.  Since I have a free Dropbox account, I just configure Thunderbird to put the mail data under the Dropbox folder on both machines.  Mails received on either platform will then be automatically synced to the other.

Account Setting: Define Mail Data Folder under Dropbox

Mail Folder created under Dropbox Folder

You may click the images above or here for a free Dropbox account.


  • Thunderbird MUST NOT be run simultaneously on both machines; otherwise, mail data will be messed up.
  • The sync process may take from a few seconds to a few minutes depending on the size of the data and the speed of the network.
  • Therefore, it is better to wait a few moments before opening up Thunderbird on the other platform until Dropbox’s Files Sync action is completed.