According to the MIME grammar, the slash (/) character is one of the tspecials
(token specials) which MUST be quoted inside a MIME header. Thus the proper
form of the above header is:
Content-Type: MULTIPART/MIXED; boundary="-----12/01/92-14:05:26-----"
Maybe the next version of MIME needs to make a recommendation that boundaries
should be quoted by MIME generators, whether you think it's needed or not.
Alternatively, how about a short example algorithm for generating a "correct"
random boundary? Not required of course, but a recommendation. This could
solve a lot of future hassles. If a MIME implementor is unsure, then they
can just use the suggested algorithm.
Just a couple of thoughts.
Cheers,
Rhys.