Hi Matthias

Sorry for the long response time. I kept forgetting to test it but now it has become more relevant unfortunately.

First I took the code I had already, made the change suggested and ran it with incremental = False. That gave some regexp error.
Then I created a fresh directory and tried the same which failed with:

  File "./gui.py", line 358, in run
    self.func(self.options, self.prog, True)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 527, in doBackup
    backup.backupTo([options.start_date, options.end_date], overwrite, include_labels, exclude_labels)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 352, in backupTo
    self.doBackup(date_range, include_labels, exclude_labels)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 339, in doBackup
    self.fetchAllMail(date_range)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 311, in fetchAllMail
    self.fetchAllLabel(date_range, exclude_labels)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 300, in fetchAllLabel
    self.fetchMailByLabel(l, date_range)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 222, in fetchMailByLabel
    self.fetchMail(uid, seen, label, size)
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 279, in fetchMail
    self.flushFetchMailRequest()
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 270, in flushFetchMailRequest
    self.processMail(rfc[1], *self.fetchBuffer[i])
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 240, in processMail
    mid = getMID(mail.get('message-id'))
  File "/home/tol/Dropbox/bin/backup-gmail/backup_gmail.py", line 45, in getMID
    tmp = re.findall('(<[^>]+>)', env)
  File "/usr/lib/python2.7/re.py", line 177, in findall
    return _compile(pattern, flags).findall(string)
TypeError: expected string or buffer

Then I downloaded the newest (?) with 'bzr branch lp:backup-gmail', added the suggested changes, created a fresh backup dir again and it failed with:

  File "/home/tol/backup-gmail/backup_gmail.py", line 562, in <module>
    doBackup(options, TerminalProgress())
  File "/home/tol/backup-gmail/backup_gmail.py", line 532, in doBackup
    backup.backupTo([options.start_date, options.end_date], overwrite, include_labels, exclude_labels)
  File "/home/tol/backup-gmail/backup_gmail.py", line 355, in backupTo
    self.doBackup(date_range, include_labels, exclude_labels)
  File "/home/tol/backup-gmail/backup_gmail.py", line 342, in doBackup
    self.fetchAllMail(date_range)
  File "/home/tol/backup-gmail/backup_gmail.py", line 314, in fetchAllMail
    self.fetchAllLabel(date_range, exclude_labels)
  File "/home/tol/backup-gmail/backup_gmail.py", line 303, in fetchAllLabel
    self.fetchMailByLabel(l, date_range)
  File "/home/tol/backup-gmail/backup_gmail.py", line 222, in fetchMailByLabel
    self.fetchMail(uid, seen, label, size)
  File "/home/tol/backup-gmail/backup_gmail.py", line 282, in fetchMail
    self.flushFetchMailRequest()
  File "/home/tol/backup-gmail/backup_gmail.py", line 273, in flushFetchMailRequest
    self.processMail(rfc[1], *self.fetchBuffer[i])
  File "/home/tol/backup-gmail/backup_gmail.py", line 243, in processMail
    mid = getMID(mail.get('message-id'))
  File "/home/tol/backup-gmail/backup_gmail.py", line 45, in getMID
    tmp = re.findall('(<[^>]+>)', env)
  File "/usr/lib/python2.7/re.py", line 177, in findall
    return _compile(pattern, flags).findall(string)
TypeError: expected string or buffer

I am totally lost when it comes to regexps so I cannot find any errors myself. Is there another branch I should try or do you have any other suggestions?