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MailStore – limitations when archiving from Thunderbird

ID: 13738

Summary

When archiving from Thunderbird, you may encounter the following problems or limitations:

  1. The archive content does not match the Thunderbird profile content.
  2. No messages will be archived at all.
  3. Some folders are missing in the archive.
  4. Folders do have the wrong name in the archive.
  5. Moved messages are not moved in the archive.

Cause

  1. Thunderbird does not have an API, that can be used to acces the profiles and accounts. MailStore has to search for the profile directory on the local drives and has to analyze the files found there. Thunderbird stores the messages of each folder in mbox files. This is a container format which can hold multiple e-mail messages. Some folder and message information are stored in Mork database files with the file extension MSF, which are not read by MailStore.
  2. Thunderbird supports two message store types, which define how messages are stored on disk. The mbox type and the newer maildir type. MailStore only supports archiving messages from accounts that are using the mbox message store type.
  3. Only messages in folders that have been stored locally by Thunderbird can be taken into account when archiving.
  4. When messages are moved in Thunderbird, a copy of the message will be created in the target folder and the source message will be flagged as removed in the Mork database of the source folder. The source message itself remains in the mbox file but is not shown by Thunderbird anymore. Since MailStore does not read the Mork database file, it is not able to detect the moving of the message and skips the message in the new folder. MailStore only archives one appearance of each message per source.
  5. In case an IMAP folder name contains non ASCII characters, these characters must be encoded in modified UTF-7. Thunderbird uses these folder names with the encodeded characters as file names of the mbox files on the file system. MailStore uses the file names of the mbox files as folder name in the archive.
    Local folders in Thunderbird that contain special or non-Latin characters that cannot be used as filenames in the file system may have a different name in the archive. The chosen foldername is only stored in the Mork database file which is not read by MailStore and MailStore is only able to read the replacement name from the file name.
    Root folder names of local folders that contain special or non-Latin characters are not shown correctly.

Resolution

  1. Archive the message directly from the e-mail server. The IMAP protocol should be preferred.
  2. The message store type for new accounts can be set in Options > Advanced > General > Advanced Configuration > Message Store type for new accounts.
  3. Are folder missing in Thunderbird that should be there, e.g. are visible in the webinterface of the provider, verify that in Options > Account Settings > Account > Server Settings > Advanced the option Show only subscribed folders is disabled.
    Empty folders will not be synchronized into the archive. In case empty folders do have subfolder which do have messages, the filled subfolder may not be sychronized. To avoid this, move at least one message into the empty base folder.
  4. In Thunderbird, folders can be compacted by right clicking on a folder and selecting Compact. Moved messages then will be removed from the mbox file, and MailStore is able to detect the moving of the message.
  5. This behavior is caused by Thunderbird and can’t be changed.