There are a number of older yahoo groups with useful mails. Unfortunately, the current interface makes it very difficult to search. This post describes how to download the mails into a standard mbox.

First, download the prerequisites with brew (on a mac) or your favorite package manager.

brew install dash
brew install cpanm
brew install procmail
sudo cpanm -v JSON

Next, download the mbox_yahoo scripts.

The heart of the download shell script is this excerpt which shows the “magic” URL.

for i in $( seq $MIN $MAX ) ; do
	curl -4${GROUP}/messages/$i/raw > message_$i ;
	sleep 1;
done ;

The script (from the same link) extracts the ygData.rawEmail portion of the json encoded data.

use JSON;
use Data::Dumper;
use HTML::Entities;

# 20140512 (
# this script helps get mail back from the evil clutches of yahoo.
# do whatever you want with it

binmode STDOUT, ':utf8';
my $json = <>;

if( $json !~ /^{"ygPerms":/ ) {
	die "no can do, buckeroo";

my $entity = decode_json( $json );

my $message = join( "", split( /
/, $entity->{'ygData'}->{'rawEmail'} ) );
print decode_entities( $message ), "\n";

Stitching together and formail (a part of procmail) gives us a standard mbox.

cat message* | perl | formail >> archive.mbox