From Wiktionary: mischan (pl mischans): a message posted accidentally to the wrong IRC channel.
When people have multiple communication channels available, it's inevitable that some message will be sent to the wrong one. Sometimes that's relatively benign (a public message that accidentally gets sent privately and needs to be resent), other times it's quite serious (a private message gets a wider audience, thus revealing secrets or making embarrassing statements). On MUDs, mischans are a part of life; Threshold RPG has an extensive thread on its forums dedicated to the funniest such events. In email, it's not nearly as common, but it is known.
I used to mischan quite frequently on Threshold - a consequence of having access to a large number of channels, and also having a tendency to snap off very quick replies. These days, I have just as many channels and snap off just as quick replies, but almost never mischan; but the solution applied does not conveniently translate to the alternate medium of email. Yet emails are just as easy to misdirect, and considerably more serious (everyone knows about the dreaded Reply All). I use GMail for all my mailing lists, for the threaded conversation view; it's excellent, but doesn't have any protection against mischans.
The solution is to make use of color. Train your brain to associate certain colors with certain topics or channels, and then any time there's a mismatch, the brain will instantly recognize it - before it's too late. Threshold RPG already has a feature for applying color to channels, but it applies only to what the server sends you; there's no way, normally, to change the color of your typed text. (Shameless plug ahead...) My MUD client, RosMud++, has a means of configuring the input color. From the Options|Color dialog, simply enter channel names and select the corresponding colors - and watch as your brain becomes accustomed to seeing text in the color it's going to end up. Unfortunately, it's not so easy with email.
Two solutions recommend themselves. The first is to do the same as for the MUD; assign a color to each list, and get used to typing 'python' only for this color, and 'savoynet' only for that one. This requires quite a bit of configuration but could give excellent dividends. The other is to have a pseudo-address 'list' that can be used whenever you reply to an email, and which will send to the list address cited in the email header.
This isn't a different form of Reply button (Reply, Reply-All, Reply-List), although it could perhaps be implemented thus; it should be possible to send something to some address "and the list", where the latter is automatically filled in from the header. As a pseudo-address, 'list' could be permanently aliased to 'whatever the RFC 4021 header List-Post specifies', allowing the fingers to become accustomed to replying "to sender" or "to list" very easily. Fighting human nature is doomed to failure; working with the way the brain and fingers already want to work promises far more success.