For example a Vinux user wroted following letter with vinux-support 
list, Vinux is an accessible Ubuntu based distribution with visual 
impaired users:
"Hello all.

I am facing a very interesting problem with thunderbird right now.
Fortunately this is the email Id I use for Orca and many other mailing 
list and it is the one which is working fine.
Well, what has happened is that till today morning I could perfectly use 
Orca with thundirbird.
I have two accounts, <email address hidden> (the current one from which I 
am mailing ) and <email address hidden>, the one which is in question.

The problem is that today evening I came back from work and as usual I 
moved my .thunderbird folder from my work pc to the home pc.
I generally compress the entire folder to a file called 
.thunderbird.tar.gz and copy it to my home machine.
I opened the inbox expecting none of the kind I am experiencing now.
When I open the treeview of hackingkk and go to the inbox, I can tab and 
start using the up and down arrow to navigate the list of emails.
But when I open <email address hidden> and hit down arrow to inbox, it takes a 
few seconds to announce "inbox".
Then the big problem starts.
I press tab and wait and wait and wait!
Orca does not read any thing after that.
I press down arrow and again waited for 30 minutes but no response.
I pressed the end key and what do i find?
After 20 minutes of waiting, Orca reads the subject of an unread message.
This means that the sorting of my mailes has changed!
The latest emails have gone down and the mails from 2006 are at the top.
How can this happen?
Secondly, I have ubuntu 10.10 on my office pc and 9.04 (vinux ) on my 
home pc.
But all said and done, I did not find any problem with Orca till morning.
Nothing has changed.

So how is it possible that Orca refuses to read message list on one 
inbox and does not do the same on another?
Well in krmane I have 30000 emails and in hackingkk its about 25000?
But till morning every thing was perfectly ok!
Can some one solve the suspence?

Happy hacking.
Krishnakan"
I am not full sure this prewious quoted problem is Thunderbird 3.1.7 
related, but the second problem is absolute sure:

And another accessibility related problem with vinux-support list too:
"I also see in thunderbird 3.1 that the search combobox (ctrl + k) is 
not very accessible.
For example in the previous version, I could just do an alt + down arrow 
and set which ever parameters I like, such as subject, sender, body etc.
This is not possible with the latest 3.1 with latest stable orca.

Happy hacking.
Krishnakant"

Well, the slow list navigation issue is fixed with Orca development 
version, you are right, but this is not solving this slow list 
navigation problem under Lucid and Maverick. Not fixed yet another 
problems (for example if an user opening a message, unable to read the 
message with arrow keys without not using the new tab option with 
Thunderbird). This is working right with prewious 3.0.10 release too 
(existing message window, message presenting option working right too).

Attila

On Sunday 12 December 2010 12:34 PM, Hammer Attila wrote:
 > Hy,
 >
 > Your problem is happened because in Lucid-security repository the 
original awailable Thunderbird version is upgraded with 3.1.7 release.
 > I sent now following letter with Bill and Tony, unfortunately I see 
only this day morning this upgrade, because I am not in home with 
prewious days:
 > "This day morning in Lucid security original Thunderbird version is 
upgraded with 3.1.7 release.
 > With Orca 2.30 version this change resulting slow list navigation, 
similar with Maverick Orca 2.32 version.
 > If a folder have lot of messages, the focusing, navigation operations 
is very slow after upgrade.
 > See following bug:
 > https://bugzilla.gnome.org/show_bug.cgi?id=633104
 >
 > I don't no now Orca 2.32 maintenance version containing the final 
this slow navigation related committed patch or not. If yes, perhaps 
need upgrading Orca version with latest