Dmitry Jemerov's Weblog

Thunderbird support in OmniaMea

We've been getting quite a few requests for implementing Mozilla Mail/Thunderbird support in OmniaMea, and today I investigated our options for that. I'm not too much of an expert on Mozilla development, so any comments and additions are highly welcome.

The main advantages and disadvantages of Mozilla as compared to Outlook are clear. The advantage is that Mozilla is open-source. The Outlook plugin has been a constant source of reliability and stability problems both for OmniaMea and for Outlook, and in many cases we had to resort to guesswork - "probably the incorrect behavior is caused by the fact that we're doing this wrong, so let's rewrite it that way". On the other hand, with Mozilla we'll be able to debug both sides of the integration, and clearly understand the reasons for all the problems.

However, the main disadvantage is that while Mozilla has a rich set of internal XPCOM interfaces, XPCOM does not support out-of-process calls, so we won't be able to call Mozilla APIs directly from the OmniaMea process.

The basic level of integration - importing the folder structure and the e-mail message and letting you read your e-mail in OmniaMea - can be implemented by parsing the mail database directly, without any calls to the mail client API. Integration at that level can be done for basically any client, and does not require too much effort. However, the utility of that is limited - you'll be able to read, search and categorize, but how convenient will it be if you'll have to switch to a different program for writing messages and replying?

The only project I've found which provides cross-process support for XPCOM is Blackwood Connect. However, this project is targeted at Java (and it's not clear how easy would it be to use it from .NET), and it looks like the project died before reaching version 1.0 (the latest release is dated mid-2001). Doesn't look like a good foundation for what we need.

Another option is to implement an XPCOM plugin that runs inside Mozilla (and thus has complete access to its internal API) and communicates with OmniaMea through some proprietary channel. The only problem with that is implementation difficulty. Looks like the effort to create both the Mozilla side of the integration and the OmniaMea side is more than we can afford to spend before the release of 1.0.

And finally, we can use Simple MAPI. It provides the main missing part of the "import the database directly" solution - creating messages. And that's it, basically. We can send messages and attachments, but even the simple function of deleting messages is not supported by the Mozilla implementation of Simple MAPI. And the slightly more complex stuff (marking messages as read, moving messages between folders) is outside the scope of Simple MAPI altogether. However, the advantage in supporting Simple MAPI is that it is implemented by many other mail clients besides Mozilla.

So, basically those are the options I've discovered. If I missed anything, please comment!