Some help understanding this filter please

[Matthias Andree]

Am 12.11.21 um 04:23 schrieb hput via bogofilter:
> This was taken from /usr/share/doc/bogofilter/examples/contrib
> procmailrc.example.
>
> ## Silently drop all completely unreadable mail
> :0:
> * 1^0 ^\/Subject:.*=\?(.*big5|iso-2022-jp|ISO-2022-KR|euc-kr|gb2312|ks_c_5601-1987|windows-1251|windows-1256)\?
> * 1^0 ^\/Content-Type:.*charset="(.*big5|iso-2022-jp|ISO-2022-KR|euc-kr|gb2312|ks_c_5601-1987|windows-1251|windows-1256)
> spam-unreadable.in
>
> It goes well beyond my meager grasp how procmail works.  But first I

For other explanations about bracketing, Tomaž's e-mail is good.

Those two lines are or-ed with the 1^0, and it's explained in one of the
procmail manpages IIRC.

However, I think it best to ditch all references to procmail and contrib
with the next bogofilter release.
Procmail hasn't been maintained in 20 years, and people continue to
shoot their feet with it,
and hardly anyone configures proper error trapping, which is something
you need to do yourself, including proper return codes.
It's doable, but error-prone (which error handlers should not be) and
long-winded.

Much easier to use some other filtering package, for instance, maildrop.