As part of trying to not read some mailing lists for a while, I was recently going through my .procmailrc. Doing this was eye-opening. It's not that my .procmailrc was messy as such, because I don't have rules that are sophisticated enough to get messy (just a bunch of 'if mail is like <X>, put it into file Y' filtering rules). Instead, mostly what it had was a whole lot of old, obsolete rules that haven't been relevant for years.

Looking back, it's easy to see how these have quietly accreted over time. Like many configuration files, I almost never look at my .procmailrc globally, scanning through the whole thing. Instead, when I have a new filtering rule I want to add, I jump to what seems to be the right place (often the bottom) and edit the new rule in. If I notice in passing what might be an obsolete filtering rule for a type of email that I don't get any more, usually I ignore it, because investigating is more work and wasn't part of my goal when I did 'vi .procmailrc'.

(The other thing that a strictly local view of changes has done to my .procmailrc is create a somewhat awkward structure for the sequence of rules. This resulted in some semi-duplication of rules and one bit of recent miss-classification, when I got the ordering of two rules wrong because I didn't even realize there was an ordering dependency.)

As a result of stubbing my toe on this, I now have two issues (or problems) I'm considering. The first is what to do about those obsolete rules. Some of them are completely dead and can just be deleted, but others are for things that just might come back to life, even if it hasn't happened for years. There is a part of me that wants to preserve those rules somewhere, just in case I want them again some day. This is probably foolish. Perhaps what I should do is save a backup copy somewhere (or just check my .procmailrc into RCS first).

The second is how much of a revision to do. Having now actively looked at the various things I'm doing and want to do in my .procmailrc, there's a temptation to completely restructure it by splitting my rules into multiple files and then including them in the right spots. This would make where to put new rules clearer to future me, make the overall structure much clearer, and make it simpler to do global things like temporarily divert almost all the mailing lists I get off to files (all those rules would be in one file, so I'd either include it or not include it in my .procmailrc). On the other hand, grand reforms are arguably second system enthusiasm showing. It might be that I'd spend a bunch of time fiddling around with my mail filtering and wind up with a much more complicated, harder to follow setup that basically did the same thing.

(Over-engineering in a fit of enthusiasm is a real hazard.)

PS: applications to other configuration files you might have lying around are left as an exercise for the reader, but I'm certainly suspecting that this is not the only file I have (or that we have) that exhibits this 'maintained locally but not globally' slow, quiet drift into a swamp.