Filename of a maildir message - mailbox.Maildir

How can I safely, and hopefully with the standard python tools for Maildir, find the complete filename and path of a Maildir message. I want to write the mail-message-file to a tarfile before I delete it.

I'm importing mailbox and tarfile (++)

Context:

A list of Maildirs (created from a text file)

Looping over the Maildirs (simplified), creating a list over mails to delete, a function will take the list of mails, and one by one, append the emails to a tarfile, then delete the email.

import mailbox
# Creating the list
for maildir in maildir_list
    inbox = mailbox.Maildir(maildir, factory=None, create=False)
      # Looping over folders, if (folder = Trash)
    for key,msg in inbox.iteritems():
        my_list.append(maildir, inbox, key, foldername

Then looping over the list to append the mails to a tarfile and delete (discard) them.

    import tarfile,mailbox
    # _box is allready initialized in the previous function
    for _maildir, _box, _key, _foldername in __my_list:
        __msg = _box[_key]
        __subdir = __msg.get_subdir()
        __suffix   = mailbox.Maildir.colon + __msg.get_info()
        if __suffix == mailbox.Maildir.colon:
            __suffix = ''
        __file_name = "%s/.%s/%s/%s%s" % ( _maildir, _foldername, __subdir, _key, __suffix )

        try:
            tar.add(__file_name)
            _box.discard(_key)
        except Exception as inst:
            error_type = type(inst)
            log_text = "%s\: ERROR %s - %s" % (error_type, __file_name, inst)
            log_this( logKeySub, log_text )
            e.write(log_text + "\n")

I've looked into the python docs for mailbox and email, searched google, stackoverflow, etc. For now I'm resorting to building the path and file name with _maildir, _foldername, _key and get_info().

Edit: Based on a comment by t-8ch I've made this adjustment:

for _maildir, _box, _key, _foldername in __my_list:
    try:
        __file = _box._toc[_key]
        __file_name = "%s/.%s/%s" % ( _maildir, _foldername, __file )
    except Exception as inst:
            error_type = type(inst) # Type Exception, inst.args, inst
            log_text = "%s\: ERROR with %s/.%s - %s - %s" % (error_type, _maildir, _foldername, _key, inst)
            log_this( logKeySub, log_text )
            e.write(log_text + "\n")
            continue

A dry run proved it to work very nicely.

You can use Maildir._toc. This is a dictionary mapping the keys of mails to the path of their corresponding file. This dictionary is constructed in Maildir._refresh(). This allows to defer the reading of a mails file only on demand and thus decreases the time to refresh the list of all mails (which happens quite often).

(I did find this in the source)