In my undergraduate software engineering course, Bert Cortina, Kartik Verma, and I developed a Thunderbird plugin over the course of the semester. What we developed originally started out as a scripting language for email-related tasks, but quickly evolved into a graphical workflow-based scripting system.
Each action in the workflow is programmed as a python module, allowing infinite extensibility of the system. The model is essentially that of a pipeline: each module reads a certain type of data and passes it to the next module.
The system interfaces with Thunderbird through XPCOM, specifically PyXPCOM, since we were using Python.
The features we were able to implement by the end included:
- Parsing entire mailboxes, or individual folders (Inbox, Sent, etc.)
- Filtering emails by regular expression
- Extracting attachments
- Zipping attachments into a single zip file
DuckPond is what we internally called the project. At the end of the course, we decided to release it as open source.
The plugin sources and binary xpi are hosted on Google Code.
Note that the plugin does not work on newer versions of Thunderbird, since AFAICT, there is not a version of pythonext which is compatible with newer Thunderbird releases (please correct me if I'm wrong).