The imaplib in python 2.4 and 2.5 is not able to handle a mailbox with ACL set to lrs correctly, as it treats it the same as a mailbox opened with EXAMINE. A mailbox with lrs can save \Seen flags, a mailbox opened with EXAMINE cannot.

The attached patch is giving a proposal on how to fix it.

The current select raises an exception, in case the server tells READ-ONLY in a response. However, for lrs this is the case, but nevertheless, it is possible to save per-use state information.

With the patch this is not the case anymore. A readonly exception is only raised in case of an lr mailbox, as that is an equivalent to a mailbox opened with EXAMINE, i.e. select(..., readonly=True). A READ-ONLY in the response to a select is saved in self.is_readonly. Programs who relied on an exception being raised during select, would now need to query that variable.

In case the state was not READ-ONLY during select, but becomes at some later point during command execution, still a readonly exception is raised.

The patched imaplib was tested successfully with a slightly adapted offlineimap.

@Florian this won't go anywhere unles the patch includes doc and unit test changes.