Empty Zip Files

[Ben Wylie <sa...@benwylie.co.uk>]

I quite regularly get emails getting past my spam filter which seem to
contain empty zip files. I presume they were sent by viruses which failed to
incude themselves in the zip files they sent out.
These emails have the following code in base 64 which when opened as a zip
is just empty.

UEsFBgAAAAAAAAAAAAAAAAAAAAAAAA==

Does anyone else get these? Does it always contain the above base 64 code?
Is it possible to write a rule to block this base 64 code or does SA always
decode it first?

Thanks for your help,
Ben