[exim] Store (not deliver) messages if sent to/from an addre…

Hello:

I'm having a trouble trying to google what kind of filter I would
write if I want to *archive* and not deliver messages matching a to
and a from address.

In other words, if email is from x@??? and is addressed to b@???
then store in /foo/bar and not deliver.

Thanks for any help,
Burhan