For address books I use gContactSync and several Google Contacts. If you desperately want to avoid using Google, there is an add-on that uses a folder in an IMAP account as a way to share contacts data. Would this be of interest to you? I'd need to look it up; I don't have it to hand.

I don't know a simple answer for message filters. You can just copy their data files between machines. It would require that you have effectively identical set-ups on each of your machines, as filters will be disabled if the target folders don't exist. There is at least one add-on that can export and import these files. It can be messy since there is one settings file per account and they all have the same name.

I've never tried this with junk training files; TBH I wouldn't know which files to look for. But in principle, you could do the same as with message filters.

Some users would go about it by copying their entire profile from one machine to another. Others try using a common profile stored in Dropbox (or similar) . Both can be slow, as the profile can become quite large, and it is problematic if there is any likelihood of multiple instances being open concurrently.

Thank you very much. You've confirmed my suspicion that there is no convenient way to keep one account fully synched on multiple machines.

The junk training file is training.dat. That's easy enough to copy, but copying and pasting is exactly what I'd like to avoid, because of the tedium and probability of error (if I had a nickel for every time I copied an old file over a new one....).

If I want to avoid Google, I can also copy over the .mab files that hold the address books. Same issue as above. I'll look for the add-on you mentioned.

I don't have any good solution for the message filters. I wish Mozilla would come up with a synch tool to take care of all aspects.

Thanks again for your response.

perhaps http://portableapps.com/apps/internet/thunderbird_portable

I'll look at the portable app approach, and it might help a bit.

However, I think the best method would be for Thunderbird to enable the storage of account information (addresses, filters, etc.) on the same IMAP server where the mail is kept. That way, the user would always be synched, not matter what platform he/she is using.

Great idea. Shame IMAP is a protocol for mail, not addresses or filters.

The issue is that Thunderbird supports open protocols. The program can not upload arbitrary data to an IMAP server, It can upload the data described in the IMAP RFC published by the internet engineering taskforce.

Likewise, it can communicate with LDAP severs for addresses. Because that also is covered by an RFC. When the new address book is completed, it will have support for card-dav servers as well.

Lightning communicates with cal-dav server for calendars

Unfortunately there is no RFC for Tasks, or rules/filters. Although the IMAP specification does contain an optional additional RFC that Message rules/Filters. I know of no real IMAP servers that support it outside of Government.

Thank you for the information. At least I know what to put on my wish list.

Here's how I finally settled on a solution. It's not perfect, but it works using my free Dropbox account.

1. I installed the add-on Thunderbird Message Filter Import/Export Enhanced on each computer. I used it to export the message filters from my desktop to a file on Dropbox. I then used the add-on to import the filters to the other Thunderbird instances using that file.

2. I exported my address book to a file, again on Dropbox, and imported it to my laptop and tablet.

3. I copied the junk filter file training.dat from the default directory in C:\Users\myname\AppData\Roaming\Thunderbird\Profiles to Dropbox, and pasted it into the corresponding directories on the other machines.

Of course, I'll have to repeat the procedure periodically to keep things in synch. I know I could copy the entire default directory to Dropbox and use the profiles.ini file to point to it for each machine, but it's a huge directory that would more than eat up my free Dropbox space. It would be nice if the files named above could reside in a different, smaller directory that I could keep in the cloud, but I don't think that's possible.

I hope the Mozilla folks will find a better solution than mine.

It might be the best idea but it's very easy to make a mess This is the same problem as we always faced when more than one are working on the same document.

Me thinking: Wouldn't it be possible to only keep changes in the cloud? That would be quick to search and not so big. Regularly one could refresh local files and delete cloud-files.

I completely agree with you, and I'm not crazy about my solution.

The problem is that I know of no way to keep the active address book, junk filter, and message filters in the cloud without keeping the entire default directory there as well. That directory is colossal. It would take quite a while to copy it to the cloud, and eat up all my available space on Dropbox.

The files I'm interested in are only about a megabyte in total size, but they must reside in that directory.

Any workaround would be welcome.

If the update-process was done when Tbird isn't running, you could update just those files. You could make a script, find out which is newest and copy accordingly, run Tbird, check (after closing Tbird) if you need to update cloud-folder.

Remember that there is a msgFilterRules.dat in each account, any new .mab-files will not be copied. Keep backups!