So as to make sure that Dovecot Sieve's vacation system works Exim has to be forced to generate a "Reply-To:" header in the message (which it doesn't do by default). The current example for using the Dovecot LDA with Exim doesn't do this.
Here is a replacement example for the local_delivery transport:-
local_delivery: driver = pipe command = /usr/local/libexec/dovecot/deliver -d $local_part message_prefix = message_suffix = log_output delivery_date_add envelope_to_add return_path_add headers_add = Reply-To: ${if def:header_reply-to:{$h_reply-to:}{$h_from:}} #group = mail #mode = 0660
Basically, if the Reply-To: header exists than it merely gets overwritten with itself. If it doesn't then the header is created and the contents of the From header is put into it.
If this is not done then the libsieve over restrictive rules (requiring a "Reply-To:" header even though the RFC doesn't require it) will not allow the vacation system to work.
Steve
Computer Systems Administrator, E-Mail:-steve@earth.ox.ac.uk Department of Earth Sciences, Tel:- +44 (0)1865 282110 University of Oxford, Parks Road, Oxford, UK. Fax:- +44 (0)1865 272072