[imp] attachments not showed with IMP 5.0.18

[Michael M Slusarz]

Quoting mailing lists <listas.correo at yahoo.es>:

> I did another test with RoundCube and it has not problem showing the  
> attachment (even with the Content-Transfer-Encoding field empty)

Roundcube is badly broken then.  *Directly* from the MIME  
specification (RFC 2045 [6.4]):

    Any entity with an unrecognized Content-Transfer-Encoding must be
    treated as if it has a Content-Type of "application/octet-stream",
    regardless of what the Content-Type header field actually says.

Which makes perfect sense.  What if the content wasn't 7bit text but  
was, instead, base64 data?  Potentially showing a user MEGABYTES of  
base64 encoded data is a terrible idea.  You can only assume a part is  
in 7bit when the header doesn't exist AT ALL (RFC 2045 [6.1]).

A mail-user agent can't guess at the contents of the part.  This is an  
unexpected, and potentially dangerous action.  This is no different  
than if a message doesn't contain a MIME-Version part: even if the  
data *looks* like MIME data, it *isn't* and you can't assume as much.

michael

___________________________________
Michael Slusarz [slusarz at horde.org]