[Users] About the base64 problem with Yahoo

ghaverla ghaverla at materialisations.com
Thu Oct 17 05:05:46 CEST 2013

On Wed, 16 Oct 2013 22:06:28 -0400
Steve Litt <slitt at troubleshooters.com> wrote:

> Hi all,
> Starting in early October, a lot of Yahoo email came in base64 in the
> plain text part. I complained on a Yahoo list, and of course they
> blamed Claws.
> The problematic emails all have the following:
> Content-Type: multipart/alternative;
>  boundary="whatever jibberish"
> Content-Type:  text/plain;  charset=utf-8 
> Content-Transfer-Encoding: base64 
> The preceding two lines define the first part, the text part. Note
> that if I click the little button to read the HTML part, it's
> readable.
> Here's my question:
> * What do the RFCs say about the necessity of a mail client decoding a
>   text/plain; charset=utf-8 that's encoded base64. I'd love to be able
>   to tell them "sorry, the RFC's say that's a no-no, the bug is with
>   Yahoo for base64ing the text part of the message".

I didn't look into RFCs, but I seemed to have remembered that Base-64
isn't unique.  There are multiple versions of Base64.  The standard
Base64 encoding has + and / in it, and both of those means something
special in URLs.  I can easily imagine, that Yahoo is using some
alternate version of Base64.


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