Mailman comes with a built-in web-based archiver called
Pipermail, although it can be configured to use external,
third party archivers.
archive
This option tells Mailman whether to archive messages it receives
or not, regardless of whether Pipermail or a third party archiver
is used. Turn this off if you don't want to archive messages.
Note that senders can control whether their own posts are
archived, on an individual per-message basis. If the posted
message has a X-No-Archive: header (regardless of
value), or a X-Archive: header with a value of
No (case insensitive), then the message will not be
archived, although it will be treated as normal in all other
ways.
archive_private
Controls whether Pipermail archives are private or public.
Private archives require a valid member address and password, or a
list administrator password in order to access them. This
option has no effect when a third party archiver is used.
archive_volume_frequency
Controls how Pipermail splits messages in the archive. The most
common option is Monthly meaning a new archive volume is
started every month. Very high volume lists may want a shorter
frequency (e.g. Weekly or Daily) where as lower
volume lists may want a longer frequency (e.g. Yearly).
This option has no effect when a third party archiver is used.