[exim] Accessing the SMTP queue ID whilst processing the mes…

Hi,

I'm hoping to allow easy moderation of specific emails for non-
technical users, and have written some code which adds in headers
according to MySQL lookups that the system filter can then use to
freeze a message, but I'm stuck trying to work out how to access the
SMTP queue ID of the frozen message so I can provide a simple 'one-
click' web link to the moderator.

Is there any way to access this either from within the configure file/
ACL statement or from the system filter ?

Thanks in advance,
--
Ian Spray