From KMail to Thunderbird

Preparation

        Before you start, make sure you have the full backup. Sure, the chance is nothing would go wrong, but if it would, the backup would be something which would save your day.
Shut down the KMail process if you have it running. Make sure it has finished, not just disappeared. There was a bug when KMail IO slaves were kept running in the background even after KMail was closed, and kept updating the mail folder. You do not want any external modifications to your mail folders while you’re converting the emails.
Install Thunderbird and configure just one e-mail account (it will guide you through the account configuration upon the first start). If you use POP3 access, make sure that you click on “Advanced config” button and under the  ”Leave messages on server” uncheck the “For at most 14 days” box. This will ensure you won’t lose any emails if the conversion goes wrong and you want to get back to your previous configuration. You need this so Thunderbird creates a profile directory and you’ll know where your email will be stored.
Now close Thunderbird as well as you do not want it to modify the e-mail folders you’re converting email into.



Converting your old emails

           Before proceeding through this chapter check whether you need to convert your emails at all. If you’re using IMAP protocol to access your email, and all your emails are stored at server, you do not need to convert anything at all. All you need to do is login into your account in Thunderbird and synchronize emails with the server. Then you can proceed to customization.
If you previously configured your KMail to keep the e-mail in Maildir in MBOX format, you’re lucky and you do not have to convert anything. Just copy your mbx files to the Thunderbird mail directory which you can find in the Account Settings for your account in the Server Settings submenu.
Now if you’re like me and you used POP3 to retrieve all your e-mail from the server, and have your email stored in Maildir – you need to convert it to mbx format for Thunderbird to understand. There are zillions of scripts for this task, and after trying twenty or so of them I found a Python script kmail2thunder.py. This script even generates the Thunderbird folder structure which is very helpful when you have a complex one. Download the script, and execute it passing the -k switch followed by the path to KMail Maildirs directory, the -e switch followed by the path to Thunderbird mail directory and -i ” switch to indicate we want to convert inbox, outbox, sent and trash folders:

 python /tmp/kmail2thunder.py -k /home/radut/.kde4/share/apps/kmail/mail -e /home/radut/.thunderbird/mhbphysz.default/Mail/Local -i ''


        Note that I passed the path to the subdirectory which belongs to this specific account, as I’m converting the mail account by account. Of course you need to have Python installed (you can uninstall it after conversion if this is an issue for you, don’t worry).
After the script succeeds you should have the emails converted to MBOX format and stored in the Thunderbird folder. Start Thunderbird and see your old mailboxes intact. Note that the first start may take longer than usual since Thunderbird needs to index your mail.
If you’re happy with the conversion result, add the rest of your accounts and convert the rest of emails.
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