/etc/Muttrc.d/colors.rc is in mutt 1.9.4-3.
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 | # colors
color normal white black
color attachment brightyellow black
color hdrdefault cyan black
color indicator black cyan
color markers brightred black
color quoted green black
color signature cyan black
color status brightgreen blue
color tilde blue black
color tree red black
#color header brightgreen black ^From:
#color header brightcyan black ^To:
#color header brightcyan black ^Reply-To:
#color header brightcyan black ^Cc:
#color header brightblue black ^Subject:
#color body brightred black [\-\.+_a-zA-Z0-9]+@[\-\.a-zA-Z0-9]+
#color body brightblue black (https?|ftp)://[\-\.,/%~_:?&=\#a-zA-Z0-9]+
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