since upgrading to kmail2 v. 5.8.2 and QT 5.11.1 whenever
I close kmail the toolbar and statusbar disappear - that is
they are gone when I restart kmail

this is happening in kmail2rc file (if I turn off write permissions on that
file the toolbar and status bar remain) but I can't figure out why

Or how to restore proper behavior

BTW, this problem happens for a newly defined user on my system

any help would be appreciated

I'd suggest you file a bug report over at bugs.kde.org.

Just a shot in the dark, but did you by any chance add an "Application Menu" (the "hamburger" icon) button to your window decoration titlebar? Doing so will add "MainMenu = Disabled" to my kontactrc once I start Kontact.

If you're not familiar with modifying window decorations then this probably isn't the issue but these settings can be found via "Window Decorations -> Buttons (tab)"

thanks for the replies; this is a known bug apparently caused by QT 5.11.1 changes

if you exit kmail with CTRL-Q the toobar remains

you can fix kmail by recompiling with changes to kmmainwin.cpp; see
https://phabricator.kde.org/D14454