I've used grep to search through my mbox-format emails for decades, but
I've run into a case where it seems to be ignore a text mailbox
because, I guess, it thinks it is "binary" (I think ignoring binary
is a default in my aliases file).
grep -Pr 'Game:\s+NCSOFT' *
and it ignored a mailbox named 'Domain': that contained the
" =E2=80=A2=09Game: NCSOFT"
Domain: Non-ISO extended-ASCII text, with very long lines
If I used "-Par" it finds it.
It seems that grep believes the file to binary and ignores it, though
"file" calls it "text".
grep (GNU grep) 2.21.31-adf9
Maybe grep is being a bit overzealous in calling files 'binary'?