Mutt has a few configuration options that make dealing with large amounts of mail easier. The first thing you must do is to let Mutt know what addresses you consider to be mailing lists (technically this does not have to be a mailing list, but that is what it is most often used for), and what lists you are subscribed to. This is accomplished through the use of the lists and subscribe commands in your muttrc.
Now that Mutt knows what your mailing lists are, it can do several things, the first of which is the ability to show the name of a list through which you received a message (i.e., of a subscribed list) in the index menu display. This is useful to distinguish between personal and list mail in the same mailbox. In the $index_format variable, the escape ``%L'' will return the string ``To <list>'' when ``list'' appears in the ``To'' field, and ``Cc <list>'' when it appears in the ``Cc'' field (otherwise it returns the name of the author).
Often times the ``To'' and ``Cc'' fields in mailing list messages
tend to get quite large. Most people do not bother to remove the
author of the message they are reply to from the list, resulting in
two or more copies being sent to that person. The ``list-reply''
function, which by default is bound to ``L'' in the index menu
and pager, helps reduce the clutter by only replying to the
known mailing list addresses instead of all recipients (except as
specified by Mail-Followup-To, see below).
Mutt also supports the Mail-Followup-To header. When you send
a message to a list of recipients which includes one or several
subscribed mailing lists, and if the
$followup_to option is set, mutt will generate
a Mail-Followup-To header which contains all the recipients to whom
you send this message, but not your address. This indicates that
group-replies or list-replies (also known as ``followups'') to this
message should only be sent to the original recipients of the
message, and not separately to you - you'll receive your copy through
one of the mailing lists you are subscribed to.
Conversely, when group-replying or list-replying to a message which
has a Mail-Followup-To header, mutt will respect this header if
the
$honor_followup_to configuration
variable is set. Using list-reply will in this case also make sure
that the reply goes to the mailing list, even if it's not specified
in the list of recipients in the Mail-Followup-To.
Note that, when header editing is enabled, you can create a
Mail-Followup-To header manually. Mutt will only auto-generate
this header if it doesn't exist when you send the message.
The other method some mailing list admins use is to generate a ``Reply-To'' field which points back to the mailing list address rather than the author of the message. This can create problems when trying to reply directly to the author in private, since most mail clients will automatically reply to the address given in the ``Reply-To'' field. Mutt uses the $reply_to variable to help decide which address to use. If set, you will be prompted as to whether or not you would like to use the address given in the ``Reply-To'' field, or reply directly to the address given in the ``From'' field. When unset, the ``Reply-To'' field will be used when present.
The ``X-Label:'' header field can be used to further identify mailing lists or list subject matter (or just to annotate messages individually). The $index_format variable's ``%y'' and ``%Y'' escapes can be used to expand ``X-Label:'' fields in the index, and Mutt's pattern-matcher can match regular expressions to ``X-Label:'' fields with the `` y'' selector. ``X-Label:'' is not a standard message header field, but it can easily be inserted by procmail and other mail filtering agents.
Lastly, Mutt has the ability to sort the mailbox into threads. A thread is a group of messages which all relate to the same subject. This is usually organized into a tree-like structure where a message and all of its replies are represented graphically. If you've ever used a threaded news client, this is the same concept. It makes dealing with large volume mailing lists easier because you can easily delete uninteresting threads and quickly find topics of value.