I use KMail, and I have mail from Local Folders and an IMAP account. For the IMAP account, I have Download all messages for offline use enabled. My understanding is the offline IMAP messages are stored in ~/.local/share/akonadi.
I want to back up the offline IMAP messages in case my email provider has a problem. I know that Akonadi provides a database for KDE applications, but I don't want to deal with Akonadi just to back up my messages. (I know I could backup ~/.local/share/akonadi, but I'd prefer a simpler solution.)
Does ~/.local/share/akonadi/file_db_data/ contain all the messages as text files in the numbered subdirectories?