MIME specifies that the boundary string between body parts
must be a string which does not occur in the body part
itself. This goal can be achieved in two ways:
(a) Try out different boundary string, until a string can
be found which does not occur.
(b) Select a sufficiently long random boundary string,
that the probability that it occurs in the body
part is negligible. This method is not really
permitted according to RFC 2046.
I have an impression that many mail programs
use method (b). And that some use method (b) but
do not even select a really random boundary string.
--
Jacob Palme <jpalme(_at_)dsv(_dot_)su(_dot_)se> (Stockholm University and KTH)
for more info see URL: http://www.dsv.su.se/jpalme/