Rated 5 out of 5 stars

Please have a look at the Thunderbird error console. There are hundrets of entries for "account colors". This might also be the reason why account colors is sometimes not working correctly after a restart of Thunderbird, so that the Add-On's settings must be set again.
Error: uncaught exception: [Exception... "'[JavaScript Error: "too much recursion" {file: "chrome://accountcolors/content/ac-3panewindow.js" line: 371}]' when calling method: [nsIMsgCustomColumnHandler::getRowProperties]" nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)" location: "JS frame :: chrome://accountcolors/content/ac-3panewindow.js :: anonymous :: line 371" data: yes]

This review is for a previous version of the add-on (3.2). 

This is probably caused by interaction with another add-on that uses the custom column handler interface. Please can you tell me which other add-ons you are using.