One of the beauties of Thunderbird is its mail data are both Mac and PC compatible. One can simply copy the mail data from one platform to the other and then open it without any problem.
Like many others, my desktop is a Win-7 based PC and my portable is a Mac. Since I have a free Dropbox account, I just configure Thunderbird to put the mail data under the Dropbox folder on both machines. Mails received on either platform will then be automatically synced to the other.
Account Setting: Define Mail Data Folder under Dropbox
Mail Folder created under Dropbox Folder
You may click the images above or here for a free Dropbox account.
NOTE:
- Thunderbird MUST NOT be run simultaneously on both machines; otherwise, mail data will be messed up.
- The sync process may take from a few seconds to a few minutes depending on the size of the data and the speed of the network.
- Therefore, it is better to wait a few moments before opening up Thunderbird on the other platform until Dropbox’s Files Sync action is completed.
How To Mac 