With Cyrus, I can create folders with subfolders with dots in their name correctly. That also works with Thunderbird. So, it looks like it's not Thunderbird's fault.
The problem with Cyrus is that Cyrus refuses to accept a large number of emails that it considers to be not "standard compliant". E.g. it rejects specific "From"-headers that Mozilla is using. Even though this applies to only 1% of all email, it is still an enormous number of them.
On the web, it is suggested to use a sed-script to remove these offending headers from the mbox files before copying them to Cyrus. However, Mozilla's own index files (.msf) get confused if the underlying mbox files change, and some emails just disappear. (There are also emails disappearing if the .msf file is deleted).
BTW, mbox/Dovecot does not support hierarchical folders. Nicolas KOWALSKI wrote:
Public Mailing Lists <lists@lists.cichon.com> writes:No, I can't change the dots to underscores, sorry. Cyrus appers to be really smart about dots and change them secretly to charets, or something. Is it possible to have any other imap server do this the same way, i.e. transparently?With Dovecot, you can use a namespace to define '/' as the hierarchy separator, even if Maildir is used as storage. BTW, what are the problems with Cyrus ?