/usr/share/mailutils/mh/scan.default is in mailutils-mh 1:3.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | %; Default scan format GNU MH.
%;
%; GNU Mailutils -- a suite of utilities for electronic mail
%; Copyright (C) 2003, 2010-2012, 2014-2017 Free Software Foundation,
%; Inc.
%; Distributed under GPLv3+. See <http://gnu.org/licenses/gpl.html>.
%;
%; NOTE: This file is not actually used and is supplied for your reference
%; only. It shows the default format string, which is compiled into
%; "scan".
%4(msg)\
%<(cur)+%| %>\
%<{replied}-%?{encrypted}E%| %>\
%02(mon{date})/%02(mday{date})\
%<{date} %|*%>\
%<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>\
%<(zero)%17(decode(friendly{from}))%>\
%(decode{subject})%<{body}<<%{body}>>%>
%; End of scan.default
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