Mutt and monthly delete old messages

[Mark Fletcher <mark27q1@gmail.com>]

Hi

I'm aware there are large number of proponents of Mutt on this list, and 
so I thought I'd give it a whirl.

I've got fetchmail downloading from my gmail account only the folder 
that I have Google Inbox putting all the list messages for this list in, 
and forwarding them to my local user on my PC. I use exim4 for an MTA on 
my machine, running Jessie.

Net result -- all the list mails, except the ones I send (thanks Google) 
in one muttable folder on my machine. For now this is great, but the 
number of mails will get out of hand. It's not really sensible to 
aggressively delete mails after reading them as you never know when a 
thread is going to end, and it's nice to be able to look back at the 
previous messages in a thread. Say what you like about Google Inbox (and 
I am sure some of you will), at least there you can mark messages as 
Done and if the thread gets resurrected the previous messages will 
return so you can scroll back to them if you want. On the other hand I 
thought I'd try mutt because it seems to make a far better job of 
helping me stay within the rules of this list when posting.

So I was thinking of implementing a policy of deleting messages from 
this mail folder on my PC (the one Mutt is looking at) on a say monthly 
basis. Looking at the mutt documentation I think it can do something 
like that but it seems to be assuming separate folders within one's 
local mail file, and I am just using the mail file directly. Call me 
thick but I'm not understanding how I could get mutt to do this, and 
certainly not how I could get it to do it automatically. I want this to 
happen in the background, I don't want to have to initiate it. I am 
using the default style of mail file mutt sets up if you don't ask it to 
do anything special when you first launch it after installing from the 
Debian repository.

Any advice on the smoothest way to get background archiving (which in 
this case means deletion) of old messages in this scenario? I'm not 
married to a Mutt solution, any solution that will automatically delete 
the right mails at the right time is fine. Gene I think you have 
mentioned in the past that you have something in place for this don't 
you?

Thanks

Mark