Updated on July 14, 2014:

1) I tested this again on my system today:

OS: Windows 7,  LMDE Cinnamon Edition (with debian testing mirrors enabled)
IMAP Client: Thunderbird (on Windows) 24.6 and Icedove 24.5.0  (on LMDE)
IMAP Server: Yahoo

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Well, now a days, dual booting (windows and linux), if not triple booting, is common on personal machines for many users. Here, I try to share a tip for sharing thunderbird mails between Linux and windows without duplicating profiles. My machine has windows 7 and ubuntu 10.10 (Maverick). I have all the mails (i.e thunderbird profile) on Windows partition. I could have set up the same thing on Linux. Unfortunately, windows doesn't allow linux partitions to be written the way linux does. In linux, one can write to NTFS or FAT partitions. So it is better to set up thunderbird profile on windows first (IMAP or POP3). In windows 7, usually thunderbird (tb) profile path is C:\Users\user ID\AppData\Roaming\Thunderbird\Profiles. In ubuntu (/home/user ID/.thunderbird).

I assume user knows following things:

1) NTFS-3G is installed on linux machine and windows p
artitions are mounted (either automatic or manual)
2) Tb is installed on both the OS (Windows and Li
nux) and profile is set up on windows machine with all the mails stored on windows partition. Do not set up profile or mail on linux yet.

Here is the procedure:

1) Boot into linux and mount windows partitions.
2) On linux, start tb. When started for the first time
, tb asks you set up the accounts. Do not set up any account and close the thunderbird.

3) Now browse (with nautilus on gnome) to windows partition and find tb profile (/media/C/Users/AppData/Roaming/Thunderbird/Profiles).
4) One should see one single folder that ends with .default with 8 random letters and numbers (For eg. l7mn2zty.default -- above picture)

5) Right click on the folder and select "make link". Immediately, a short cut will appear in the same folder with name "Link to xxxxxxxx.default" wit
h a small arrow on the top indicating that it is a short cut.
6) Now cut this short cut and paste into linux tb
profile (/home/
userID/.thunderbird).

7) Now your .thunderbird folder will have 2 folders and one text file by name "profiles.ini". In addition, one may also find a small file called appreg which is irrelevant at this point.

8) Now right click on the short cut and remove "Link to" from "Link to xxxxxxxxx.default". So the short cut should look like "xxxxxxxxxx.default".
9) Note down the random number xxxxxxxx and open "profiles.ini" file with a text editor (gedit or vim). Look for the entry "path=". Replace path value (yyyyyyyy of yyyyyyyy.default) with (xxxxxxxx). Now the value should look like path= xxxxxxxx.default instead of earlier entry yyyyyyyy.default.
10) Now start the tb, now every thing should work automagically including extensions and appearance. Here I am showing my gmail IMAP mails.


11) If you are using Enigmail extension like me, you may need to disable gpg-agent in Enigmail and may have to import your key into key manager in gnome.


12) If you do not mount windows partitions before launching tb, an error will pop-out "Thunderbird is already running ....."