Aaryan Bhagat writes:
> Well in a crux when the user will resubscribe he will see its
> previous posts. We have an implementation for that already right?
I read Mark's reply, but I'm still not understanding what you are
thinking about. It doesn't seem to be the archive (which after all
may not even exist for a given list), but "check the archive" is the
standard Mailman answer to finding missed posts.
Let me take this opportunity to frame a discussion of the architecture
of Mailman 3 in the context of this thread. There are five ways that
a user with address "unsubscri...@example.net" might see a post
(whether her own or another person's).
1. via the list to unsubscri...@example.net (while still subscribed
and enabled); this will receive posts only while subscribed and
enabled.
That is, Mailman does not send "back issues" (except in the corner
case that the subscription is a digest subscriber, they'll receive
posts that have accumulated in the current digest issue up to the
time they subscribe). If the question is "does Mailman send
missed posts in the case of an interrupted subscription", the
answer is "no". It also doesn't automatically switch a
subscription to a user's disabled address if the enabled address
is disabled or unsubscribed. (This would be possible with the
current design, but I'm not sure whether it would be a bug or a
feature!)
By design, Mailman cannot do send missed posts at resubscription
time. The core keeps track of subscriptions and accepts posts and
forwards them to enabled subscribers and IArchivers *once*, then
forgets them (except for logging the event of a received post and
its forwards -- but the message itself is forgotten). Handling
temporary failures is the responsibility of the MTA, which may
retry delivery many times before giving up and returning a
"bounce" to Mailman. Mailman itself sends a post to each enabled
subscriber only once.
On the other hand, the archiver keeps track of posts, and doesn't
know anything about subscribers. It's true that core provides a
way to query a list to check if an email address is subscribed for
authentication purposes, but there is no way to get information
about posts received (or not received) by that address. Neither
the core nor the archiver records that information.
I seem to recall that in the days before the web there were MLMs
that allowed you to request that the MLM send you an archive of
past posts by mail! But Mailman was designed to take advantage of
the web, and doesn't implement that. Instead we access old posts
via the web. (Some archivers also allow downloading whole mboxes
to get a month's worth of posts.)
2. via the list to another subscribed and enabled address of that
user
3. as a direct addressee (including their "sent" folder, if you
insist you could count this as "3b")
4. on a another subscriber's or addressee's screen or printed out on
paper on their desk
5. in an archive. This is the generic answer to "I didn't see some
posts in my mailbox, how do I read them?"
In case #4, an archive, some kind of authentication (such as list
subscription) may or may not be required. But it need not be list
subscription: it's up to the archive itself to decide policy. And if
it is list subscription, neither the core nor the archive records
enough information to identify "back issues" that need to be sent.
Electronic mail delivery is the paradigmatic example of a distributed
system, and Mailman 3 just squares that. :-)
Steve
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