courier re-writing of mime boundaries, verification fails

[Daniel Kahn Gillmor]

On 02/26/2012 03:16 PM, Mike Korizek wrote:
> If courier receives an email with plain/text and HTML parts there
> happens a re-writing of the MIME boundaries.

This sounds like a bug in the Courier MTA, according to the MIME
standards for encrypted/signed mail:

 https://tools.ietf.org/html/rfc3156#section-3

   Multipart/signed and multipart/encrypted are to be treated by agents
   as opaque, meaning that the data is not to be altered in any way

See also:

 https://tools.ietf.org/html/rfc1847
 https://tools.ietf.org/html/rfc2480

> a) Is there a possibility to prevent the re-writing of the MIME boundaries?
> 
> b) If not, which are the rules of the re-writing. If I know them I can
> reverse that before the verification happens.

These questions ar probably better asked on the courier mailing lists:

  http://www.courier-mta.org/links.html

hope this helps,

	--dkg