When I started on the net, bandwidth was precious. Dialing in to the BBS with your 300 baud modem, every character was important, and anything extraneous was eliminated.
Mail in particular was terse and to the point. Most mailing lists I have been on have had a moderator or 'list mom'. Someone who enforces the rules and anyone not complying is warned or possibly kicked off the list.
From the FreeBSD Mailing List FAQ:
Please respect the fact that bandwidth is not infinite. Not everyone reads email through high-speed connections, so if your posting involves something like the content of config.log or an extensive stack trace, please consider putting that information up on a website somewhere and just provide a URL to it. Remember, too, that these postings will be archived indefinitely, so huge postings will simply inflate the size of the archives long after their purpose has expired.
Lately however more and more lists I'm on seem to have no owner willing to step up and enforce (or even define) any rules. And people posting to most lists seem extremely lazy and unaware how their behavior impacts other users.
Recently there was a big conversation on one of the lists I'm on. I complained about trimming replys as I was traveling and trying to scroll through pages of quoted conversation on a cell phone was painful.
No one listened.
Below is a typical post I see. The section in green is the reply, the section in red is the extraneous quoted material that someone was simply to lazy too delete before hitting the reply button:
This is actually not that bad. I've seen posts where I had to scroll for days. Google Groups is particularly bad at this as it adds a footer to each email, and as the reply count increases you have all this additional footer baggage as well.
I'm going to call people out on this behavior when I see it moving forward. If people don't clean up their act (and replies) I'll unsubscribe from the group. If no one cares how a list is run, I probably shouldn't care too much about the content on it.