Hello Steve Newcomb, I am not the mailutils maintainer, but just came across you report.
The information you supplied might not be enough for the maintainer to track down the issue, and it might be related to the content of your mail directory. You supplied the dmesg output, but even when the crash shows up in libc-2.28.so, the problem normally is the application calling into libc. Maybe you could install a core dump collector like 'systemd-coredump'? That way you should receive a maybe helpfull backtrace in the output of your journalctl. When installing the debug symbols like described in [1] that information should be even better. Kind regards, Bernhard [1] https://wiki.debian.org/HowToGetABacktrace#Installing_the_debugging_symbols
