exim I

exim is the mail filter at work. I had a good time this evening trying to get the system_filter to work properly for the customer care guys.

Question that's not fully answered in the documentation:
Is there a difference between $sender_address and $header_sender ?

I think there is, because the filter (using $sender_address) hasn't been catching the emails, which have a different Sender: and From: value. I#ve changed the test line to check for $header_sender - won't make any difference if it's wrong, because the mails haven't been going to right place at the moment anyway.

The documentation on exim's string expansion doesn't go into any detail about which $header_n strings are legal, and which ones aren't. My guess is that legal values are taken from some RFC, but it's not for sure.

Oh yeah, and unlike our shorewall, it doesn't look like there's a way to get exim to check the system_filter file for syntax errors. That's because the file is continually live, so watch out - if you mistype something, mail will stop being delivered. So the only way to see if there /is/ a problem is to tail -f exim_main.log; sudden silence means your system_filter is broken.