I think as Jim suggested this might do the trick (minor change to syntax)
     G_BLOCK_SKIP "*,!HIDDEN@em.destination.domain"

ChrisP.]


On 10/12/2015 6:47 a.m., Peter Dyke wrote:
> The administrator of one (and only one) of the domains on our SM has 
> requested that .zip attachments be blocked. [After they got hit with a 
> crypto-locker infection].
>
> g_archive_files would not work in this scenario
> g_block_files would be fine but other domains on the server do not 
> want such blocking
> g_rename_files is also not per domain, and would not really be a block 
> anyway
>
> Anyone doing this, any suggestions, or am I missing something obvious?
>
>