/usr/share/kak/rc/base/mail.kak is in kakoune 0~2016.12.20.1.3a6167ae-1build1.
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 | hook global BufCreate .+\.eml %{
set buffer filetype mail
}
addhl -group / group mail
addhl -group /mail regex ^(From|To|Cc|Bcc|Subject|Reply-To|In-Reply-To):([^\n]*(?:\n\h+[^\n]+)*)$ 1:keyword 2:attribute
addhl -group /mail regex <[^@>]+@.*?> 0:string
addhl -group /mail regex ^>.*?$ 0:comment
hook -group mail-highlight global WinSetOption filetype=mail %{ addhl ref mail }
hook -group mail-highlight global WinSetOption filetype=(?!mail).* %{ rmhl mail }
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