:nnoremap <C-z> :term<Return> works for me (tmux in urxvt). Ctrl-Z only gets converted to SIGTSTP if the terminal has ISIG set. For example, try `stty -isig;

:nnoremap <C-z> :term<Return> works for me (tmux in urxvt). Ctrl-Z only gets converted to SIGTSTP if the terminal has ISIG set. For example, try `stty -isig; sleep 5` and try to suspend or interrupt the sleep command.