Log Message:
Update to 4.8.2. From the changelog:

- for IMAP retrievers, keep message state around for 30 days even
  if the corresponding message isn't seen. This allows users to
  have multiple rc files with different IMAP folders to retrieve
  from without losing their "seen" mail state for the folders they're
  not currently retrieving from. You no longer need to work around
  this with different getmail state directories. Thanks: ?.