I have two computers, each has Thunderbird installed.

I once set up a Thunderbird profile on computer A and configured my email accounts there (all POP3, not IMAP). The message store type is "File per folder (MBox)".

Later I copied that profile to computer B and used them in parallel.

So now both profiles still have the same name and some common data and settings, but e.g. the sent mails are only located on the computer they were written. Received mails are mostly on both computers, because the mail server keeps read messages for another month or so, which means I usually have time to download them from both machines.

My question is how to bidirectionally synchronize those two profiles again, so that at least all the data (sent/received mails) is the same on both computers? I don't want to upload the profile folders or mail files anywhere, so please suggest methods that work locally (I could of course transfer the profile folders per pendrive etc.) or over LAN.

Please note that I don't really want to migrate all my stuff to IMAP (although it would be supported) - I just want to be able to synchronize the POP3 Thunderbird clients manually, on demand over my local network or using removable storage devices.

The question is not about migrating to IMAP to keep the accounts in sync in the future, my main problem is to synchronize the past: mails that got already deleted from the server and are stored only in one local profile, and sent mails which were never stored on the server and are only located in the profile from which I wrote them.

  • If you are able to use IMAP the task is simple. I have 3 different email addresses, all in different domains from one another, I access using Thunderbird from Ubuntu Mate, Ubuntu, and Windows 7 - all are synchronized including calendar.
    – pfeiffep
    May 28, 2016 at 17:56
  • @pfeiffep But as I said, currently all my accounts are POP3. I don't know if/how I could convert the accounts.
    – Byte Commander
    May 28, 2016 at 18:48
  • 1
    What kind of mail server/provider do you have that doesn't offer IMAP in 2016? Maybe it's time to migrate to a different one. Many offer both in parallel on the same account. I don't think there's a clean solution to your problem without it. May 28, 2016 at 22:12
  • @byte Commander certainly it's your choice to stick with POP3. AFAIK the 'conversion' takes place at the originating smtp server. Your tag suggests that you also use TBird, contact your email provider and ask for the port information related to IMAP - to be safe do this in Evolution
    – pfeiffep
    May 29, 2016 at 1:14
  • 1
    Just to see if perhaps your mail server is already configured to handle IMAP, try creating an IMAP connection to it. I use Google for my mail, and when I set up on a new machine I choose IMAP, and put in my email address, if the server accepts that, then it should ask you for your password. This is just a test to see if you can do it. Like everyone else here, IMAP is the way to go for what you want, otherwise, you will need to script something or create maybe a network shared folder for the sent items and sync it there. May 29, 2016 at 20:45

2 Answers 2


The best you can do with pop3 for sync is to make sure that both clients don't delete messages from the server, then they can get both messages but this will obviously not change the past.

Not deleting messages will eventually end up with your mailbox being too large to use without big slowdowns and or timeouts, especially if its hosted by a third party who will have a specific resource allocations.

IMAP was invented to solve this problem and there are a variety of import tools depending on the specific servers used. Your service provider should be happier with your using IMAP because above about 6 months worth of email IMAP is more resource efficient and better supports multiple clients. I would ask them for advice as they will almost certainly have an import/export tool they have tested to work with their setup, if they don't then find a new provider that does provide them because without those tools you are effectively locked in.

  • You can also "leave messages on the server for xxx days", select 7, and make sure you check your mail on both computers at least once a week.
    – Jos
    Jun 1, 2016 at 11:47
  • The migration to IMAP would probably not be a problem. However, I need to synchronize my old stuff, especially mails that are already deleted from the server and sent mails, which never appeared there.
    – Byte Commander
    Jun 1, 2016 at 12:01
  • if you import both collections to a single IMAP account there will not be duplicates in the IMAP account. You might have to export the mails from thunderbird to a more mail server friendly form such as maildir or mbox. If i'm vague on details its because your IMAP provider should provide you with this information and each has their own ways. I don't expect this to be a single task , you almost certainly will still need to do quite a lot of moving around of mail manually as IMAP folders have a specific structure that doesn't cleanly map to pop3 mailboxes.
    – Amias
    Jun 1, 2016 at 16:22

Well, I don't have the time to completely dedicate a total walkthrough for you but you might be able to get away with using NIS(yp), NFS, and configuring AutoFS. Then changing your Thunderbird directory to the AutoFS partition that's mounted on the auto-mounted NFS partition.

POP has a limitation of Forward & Delete or Forward & Save... but this setup might work. I'm not sure if there's any limitations of data refreshing in Thunderbird to say for sure this will work with concurrently efforts from different machines but this... should definitely work on different machines without much intervention.

  1. Configure a NIS Server
  2. Configure a NIS Client (Server can also be client)
  3. Configure NIS Server with NFS: Create an /exports/home directory and mirror the ACLs. Then move your home folder to the NIS /exports/home folder. Once you configure the NIS Server to act as a client to it's own NIS server, it will use the /exports/home folder for your profile.
  4. Configure AutoFs using /etc/auto.master and /etc/auto.misc


/home /etc/auto.home


#   & is equivalent to your user account via Wildcard on the NIS server - Leave as &
*  -rw,soft your.nfs.srv:/exports/home/& 
#   if auto.home on the NIS server, then use a local disk autofs.
*  /exports/home/&
  1. Configure your hosts to be clients of the NIS Services on this host and configure each with the Autofs settings mentioned above.
  2. Configure Thunderbird to use a the new home directory.

Further notes to the mod that edited my post: From the autofs man page.

Map Key Substitution

An & character in the location is expanded to the value of the key field that matched the line (which probably only makes sense together with a wildcard key).

Wildcard Key

A map key of * denotes a wild-card entry. This entry is consulted if the specified key does not exist in the map. A typical wild-card entry looks like this:

*    server:/export/home/&
  • MadMike - Do not replace the content. The "enhanced notes" are appreciated but you changed the content by advising replacing "&" with your Home Directory. That comment is inaccurate to how autofs works. Autofs will use the NIS user name in-place for that directory. Thus it will resolve /home/{username} here for the /home/username on the NIS server. Jun 1, 2016 at 21:41

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