ml2json mail archive processor


The basic principle of operation of ml2json is the following:

  1. ml2json iterates over all the files in the given directory / directories / files (using the mbox_glob setting to filter files found in directories), opening each mbox file or Maildir or ezmlm archive directory in turn, iterating over the messages therein, parsing each in turn using the MIME parser which creates an object plus files in the tmp directory; the code then serializes the object to the tmp directory as well, so that the parsed state can be resumed multiple times quickly. Each object representing the collection of messages of an individual mailbox is serialized as well. The path of each mailbox is hashed using the mailbox_path_hash config option and used that way as part of the tmp path. If there's already a serialized object for a message collection object representing an mailbox, the mailbox isn't parsed again unless it has changed, but just the object deserialized (that's why subsequent runs of the script will be faster, also there will be no warnings about the mailbox/mime parsing phase then). The whole directory is also represented as a messagecollection object (a subclass specific for dirs).

  2. it then iterates over the messages in the (toplevel, i.e. directory) messagecollection object, de-serializing each parsed message object in turn, and builds an index of the messageids and replies,

  3. after that, it creates a sorted list of messages, grouped by thread and sorted according to the last reply of a thread, and iterates through that, deserializing each parsed message once again in turn and printing it as JSON (possibly saving message/rfc822 parts as another file so that it too can be accessed as a file).

For this reason, if changes to the code were done that lead to changed results from phase 1, the changes will only be seen if phase 1 is being forced to run again by eliminating its result from disk by running ml2json --cleanup, first.