If you haven’t found it yet, here’s a way to click links in a Thunderbird e-mail message with Dragon without using the mouse commands — basically, Thunderbird has a typeaheadfind.linksonly setting too.
To access Thunderbird’s version of about:config, go to Tools — Options — Advanced. Under the General tab, click the Config Editor button. Highlight accessibility.typeaheadfind.linksonly and press Enter to set it to true. Now, you can say a word in the link to open it — the link will be highlighted, and simply say “press Enter.”
Or, if the link is spelled in such a way that there aren’t any pronounceable words, you can tell Dragon to type a few of the letters, and get the same result. If there’s more than one instance of what you’re trying to say, tell Dragon to press Control G. The link will open in a new tab, at least in Firefox. I don’t know what it does with IE, because it’s been a while since I’ve used it — so long, in fact, that I still have version 6. (I have a feeling I should have upgraded to version 7, just in case, but ah well. I’ll live.)