I currently have a POP server for email, which is delivered to a Thunderbird client. This Thunderbird client stores email locally into a hierarchy of subfolders containing both emails and subfolders.
I now want to access this locally stored email from other clients. My first solution was to create an IMAP mailbox and move all the messages to the IMAP server. I wasn't able to do it because my IMAP server refused to create subfolders in folders already containing email. As the original hierarchy is quite complex, I can't modify it to try to get along with this limitation.
Are there any Linux IMAP server that would accept having both messages and subfolders in a folder?