[Exim] Customizing warning messages

Messages that are on the queue for more than 24 hours and then for
more than 48 hours generate warning messages. I know how to change
these warning messages (`Customizing warning messages') but what I
don't know is how to set the interval after which warning messages are
created.

For instance: for some hosts I want to generate warning messages, but
only 1 (after 24 hours)
For some hosts I don't want warning messages at all. (Only error
messages).

How can I do this? (I tried customizing warning messages and retry
configuration in the manual, but didn't find anything.)

Richard
--
It could be that the purpose of your life is only to serve as a
warning to others.