If your .forward file starts with "# Exim filter", then the Exim mail program can do some processing of your incoming email.

If you have exim installed, you can probably find comprehensive documentation on this in

/usr/share/doc/exim/filter.txt{,.gz}

otherwise have a look online at www.exim.org/exim-html-3.30/doc/html/filter.html or www.exim.org/exim-html-4.00/doc/html/filter.html depending on which version of exim you have installed.

Here is a simple example

1. Exim filter - do not edit this line!
2. only works for exim... others will treat it as a plain .forward file...
3. if this filter generates an error, then deliver to original address
4. as per usual

if error_message then finish endif

1. I have mail forwarded to me from an account at another machine.
2. it currently only gets spam, so automatically save to somewhere else.
3. This match is a regular expression, hence need to double escape the "."

if $header_received: contains remotehost\\.co\\.nz

and $header_from: does not contain remotehost\\.co\\.nz

then

save $home/Mail/remotehostspam 0600 seen finish

endif

1. default action - get exim to deliver as if this forward file wasn't here
2. change this to whatever address this server is accepting your mail for

deliver thisemailaddress@verisign.com finish