SUMMARY Define mbox account in /var/spool/mail/username and see error message when restarting Settings -> Kmail -> Accounts -> Receiving. Message is briefly visible in the Configure - Kontact dialog box from Settings -> Kmail -> Accounts -> Receiving. I have seen "No file specified." and something like "Cannot read /var/spool/mail/garry". It's hard to be accurate because the error message only flashes on the screen briefly. (That, in itself is a bug that should be fixed.) Add a sym link in home directory to /var/spool/mail/username and define mbox resource using that file and now no error message, but... kmail doesn't show all messages in mail box. Kmail will not delete any messages in mail box. Kmail won't show message has been read in the message list pane. STEPS TO REPRODUCE 1. $ mail garry # Any local user on this machine. Subject: Test Test EOT $ (The line that says "EOT" was produced by typing CTRL-D after enter key to start new line.) 2. Define Mbox resource in Settings -> Kmail -> Accounts -> Receiving -> Add -> Custom Account 2. 3. OBSERVED RESULT Doesn't work. Send multiple messages. Delete one in kmail. Nothing works as expected. EXPECTED RESULT Works SOFTWARE/OS VERSIONS Fedora: 5.8.16-300.fc33.x86_64 Kmail: kmail2 5.15.1 (20.08.1) KDE Frameworks 5.73.0 Qt 5.15.1 (built against 5.15.1) The xcb windowing system ADDITIONAL INFORMATION As far as I know, this simple mail format has been broken in kmail for at least 10 years. Perhaps won't fix? Withdraw option altogether? My work-around is to use the /usr/bin/mail command. I believe that program was originally released in UNIX and later in Linux well before 2000. POSIX standardized it as /usr/bin/mailx in 1997. I am unaware of any bugs in that program. Perhaps it could serve as an example how to process a mbox resource? I would be happy to assist in any way I can.