[exim] ${if exists{/home/joe/.vacation.msg}}

Hi

I am trying to make it easier for the users to activate the vacation
mechanism. My idea was that they should just add a file with the name
"vacation.msg" in here home directory, and then remove it or rename when
they are back from vacation.

In my .forward file I have written this construction

if ${if exists{/home/joe/.vacation.msg}}: CONTAINS "1"
  and personal
  and not error_message then
         mail
         to $reply_address
         subject "Vacation'"
         file .vacation.msg
         log .vacation.log
endif

But I get an error return when sending a test mail:

==========
The userforward router encountered the following error(s):

unrecognized condition word "exists{/home/joe/.vacation.msg}}:" near
line 12 of filter file

No valid addresses were generated.
==========

Is my syntax wrong or is there another way to test if a file exists?

--
Venlig hilsen
Hans Schou
tel:46923438