My "workflow" to check the mail of the lists I'm subscribed to was more or less like this:

1. Open the mailbox of the list.
2. Check the first mail of every new thread.
   1. If interesting, keep the whole thread/read it/whatever. Sometimes, flag all the thread (sort-of mark it as important.)
   2. If not, delete the whole thread.
   3. If the thread lacks a head (the first mail of the thread), is because I have deleted its previous emails (because the thread's topic wasn't interesting to me). Delete such threads.

Mutt has (or can be "taught") keybindings to delete a thread, mark it as important, mark all of it as read, and so on. I even have a macro to mark all the mail in a mailbox as read, for whenever I felt/feel lazy. But even with this helpers, handling/checking maillists has always been a chore.

There was a thing that I always wanted to have for handling mail lists: to be able to tell mutt that I'm not interested in a given thread (conversation) and that I don't want any more mail related to it in the future. To have mutt delete automatically all those headless threads.

Deleting the thread when I first see it is not a solution, since more mails related to it might be sent after I delete the thread. I always ended up killing those threads manually when they reappeared. Talking with somebody about this problem, I learned that the hivemind offers its "users" that feature; they call it muting a conversation.

After thinking about how to achieve that with mutt, I defined a plan: tell mutt to tag the threads I'm not interested into, and delete them. The only hard part was to teach mutt which were the threads to tag.

The non-interesting threads are those that lack a parent mail (the email that started the thread). These threads appear only when I delete its initial emails previously, and more email ot if arrives. The parent email is the only email in the thread that lacks a References header (I'm not 100% sure about this, let me know if I'm wrong). This is enough to build a folder hook to get rid of the extra mail of unwanted threads.

# delete not-interesting conversations
folder-hook listas/.* 'push "<tag-pattern>~A<enter><untag-pattern>~((! ~h References)|(~s fwd)|(~F))<enter><tag-prefix-cond><delete-message><end-cond>"'

That monstrosity does the following

1. Tag all the mails in the mailbox.
2. Untag (I didn't know mutt could do that) all the threads where there is at least one email in the thread that fulfills any of the following conditions:
   1. Doesn't have a References header (hence is a parent email, and it survived after I read it the first time.)
   2. Has the text Fwd in its subject. Without it the hook would delete the threads that started with a forwarded message.
   3. Are flagged. I placed it there to have a way of keeping headless threads.

Now whenever I enter to the folder of a maillist, all those pesky threads that refuse to die are automatically wiped out by my faithful mutt.

By the way, have I told you before that I really love mutt's logo?