yarikoptic/fail2ban — comment on commit ed9000c469b4554aab3e9b5365b959520096f3ba
File:  line 0
By d0ru:

I have POSIX without Content-Type declaration in s-w-l.conf.

This is how it works correctly. Added the new file 'common.conf', and these lines into s-w-l.conf without comments:
[INCLUDES]
before = common.conf

[Definition]
ContentType = Content-Type: text/plain; charset=`locale | awk -F= '/LC_CTYPE/{ print $2; }'`

actionban = printf %%b "Subject: [Fail2Ban] : banned
+ %(_ContentTypeMailHeader)s
...

I have no idea why Content-Type does make a difference.