[exim] UTF 8 From header

Hi all,

Is this a legal "From:" header?

> From: =?utf-8?b?IkVsbGEgQmFjaMOpIiA8ZGlnaXRhbEBlbGxhYmFjaGUuY29tLmF1Pg==?=

How would one extract the email address from it using Exim?

I use $rh_from: to extract the header from certain emails and this one
is breaking that. Due to the vast number of broken From: headers I see,
the processing on this header is already quite extensive and I'm
starting to think I will need to offload this processing outside of exim.

Thunderbird doesn't decode it properly; some of the other available
tools I've found either completely fail to decode it or seem to work
just fine.

Thunderbird:
"Ella Baché" <digital@???> <>
(double email address)
Other tools seem to ignore the empty address, while others just return
the input unchanged.


My current attempts to make sure I get the From header look a bit like this:

> set acl_m_headfrom      = ${if eq {${address:$rh_from:}}{} \
>                             {${sg{${addresses:$rh_from:}}{^.*:}{}}} \
>                             {${address:$rh_from:}} \
>                           }
> set acl_m_headfrom      = ${if eq {$acl_m_headfrom}{} \
>                             {${address:${sg{$rh_from:}{@(?=[^@]*@)}{X}}}} \
>                             {$acl_m_headfrom} \
>                           }

I moved to using the raw header because of segfaults when attempting the
above with some processed headers.