OT: culprit in MIME recoding and breaking signatures

[Kurt Hackenberg]

On 11/23/18 1:40 AM, Ian Zimmerman wrote:

> The winner appears to be Perl, namely the Mail::Audit module (and
> whatever other modules it relies on).  I had a couple of scripts that
> did gentle transformations of incoming mails.  The transformations were
> supposed to only ever touch the headers, but I used a Mail::Audit object
> to write back the entire message including the body.  I had complete
> trust that the body would be bitwise identical to the original, but not
> so.

What change did it make? I suppose it might use a different MIME 
transfer encoding, changing the representation but not the meaning.

Also, the most common variants of mbox are known to break cryptographic 
signatures, with the notorious ">From " escaping.