Install claws-mail-mailmbox-plugin by entering the following commands in the terminal:
sudo apt update sudo apt install claws-mail-mailmbox-plugin
Description:
mbox format mailboxes handler for Claws Mail
The mailMBOX plugin for Claws Mail provides the ability of handling existing mbox format files using the libetpan library. . Once added, these files appear like mailer's native mail folders.
Homepage: http://www.claws-mail.org
Version: 3.16.0-1
Section: universe/mail