dynamic text source for RULES and ALERTS reply

I really need some help here (please).

I need a way to create a RULES AND ALERTS reply which gets it's text/body
information from central sources on the network (eg .txt or .html files), so
that when we need to change our office closure dates for Christmas (for eg)
we don't need to update every profile separately (which takes hours).

The body needs to use each users unique signature and holiday dates though,
so the body text data needs to come from various files (some 'common' and
some 'individual (eg signatures)'.

This can't be done using the built in functions, so I figure only VBA may
provide a solution. I would really appreciate ANY help at all, as I just
spent 4 hours updating 89 individual profiles!!

Thanks in advance