I finally had some time to try out the tagging functionality. My mail (>10,000 messages) is stored/accessed via IMAP and I couldn't determine whether more than 5 keywords/labels/tags would be supported other than by trial and error so I copied a bunch of mail to a test account and began exploring by redefining the standard labels/tags in TB2b1 and by adding additional new tags for a total of ~15 which I then started applying. I then logged out, created a fresh profile and assessed whether the tags associated with particular messages were retained on the server. In my limited testing (Mac OS X), it looked like they were, but of course, I could only see them if I first defined them in the new profile.
Here are the issues/questions so far:
1. The Preferences>Display>Tag tab only displays the first 10 tags making it impossible to do any editing of the remainder of the tags. Given that a tag list may become quite long, it is critical to be able to delete tags you don't want and to be able to edit the text (e.g. to correct typos). Is there a work around such as editing a file that will help with this until the UI is fixed?
2. The position of tags in the list kept changing as I added more tags and I provisionally concluded that they were appearing in alphabetical order (from the Tags menu command or popup menu in the task bar. The problem is that the tags labeled 6-9 were affected by this as well rendering the keyboard shortcuts useless since the tag associated with them would change.
3. The behavior described in #2 leads to the question whether the tag specificity is retained on a per message basis irrespective of the tag's position in the list?
4. Displaying the Tags column in the message list shows the canonical labels for messages tagged 1-5 (i.e. important, work) instead of the redefined tag text. Examination of the message headers does show the "correct" tag is retained.
5. I was pleased to see that the tags menu ends become scrollable when the list is too long for the screen. This works nicely from the Message>Tags menu item but is not as nicely implemented from the Tags popup menu (no arrowheads, choppy motion, doesn't alway reveal the New Tag item).
All in all, I'm really excited about the tagging functionality. More to say but this post is already quite long so I'll stop for now