I find out this is a different kind of bug. Apparently the kmail package does not depend on the kdebase-kio-plugins package, and thus it can only read imap mails, not pop mails, unless such kio package is installed separately.
-- "Could not start process pop3s." https://launchpad.net/bugs/68644 -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
