Re: Google Gmail mailing list bounces

[Bob Proulx]

Eli Zaretskii wrote:
> Bob Proulx wrote:
> > If Mailman disables a subscriber due to bounces then later (due to a
> > nightly cron?) Mailman sends a notice to the recipient that their
> > subscription has been suspended
> 
> First, until that cron job runs, the victim could miss quite a lot of
> messages.

True.  Fortunately there is the archive to fall back upon if there is
a desire to look at the missed messages.

  https://lists.gnu.org/archive/html/help-gnu-emacs/

> And second, I wouldn't be surprised if that notification
> went straight to the spam folder, the way it's formatted.

The messages that were forwarded to me looked okay to me.  Good even!
What specifically about them makes them look like spam?  What would
you do differently?

The content is short enough.  Here is what it looks like:

  Your membership in the mailing list help-gnu-emacs has been disabled
  due to excessive bounces The last bounce received from you was dated
  15-Feb-2019.  You will not get any more messages from this list until
  you re-enable your membership.  You will receive 3 more reminders like
  this before your membership in the list is deleted.

  To re-enable your membership, you can simply respond to this message
  (leaving the Subject: line intact), or visit the confirmation page at

      
https://lists.gnu.org/mailman/confirm/help-gnu-emacs/f1d2d2f924e986ac86fdf7b36c94bcdf32beec15

  You can also visit your membership page at

      https://lists.gnu.org/mailman/options/help-gnu-emacs/[[redacted-address]]

  On your membership page, you can change various delivery options such
  as your email address and whether you get digests or not.  As a
  reminder, your membership password is [[redacted]]

  If you have any questions or problems, you can contact the list owner at

      help-gnu-emacs-owner@gnu.org

Seems reasonable and clear enough.

Note that I have NO ability to affect either Mailman or the
installation of it on lists.gnu.org.  I am just over on the side
talking about it with the rest of the chickens.  I can't affect any
changes to the mailed message content or format.

> > Bounce messages are the only way to detect that subscribers fall off
> > the planetary network.
> 
> That's true, but why disable their delivery on the first such message?

It never happens on the first message.

I only know what the Mailman documentation says online.  It is short
enough.  Here is what it says:

  https://lists.gnu.org/mailman/admin/help-gnu-emacs/bounce (login required)

  These policies control the automatic bounce processing system in
  Mailman.  Here's an overview of how it works.

  When a bounce is received, Mailman tries to extract two pieces of
  information from the message: the address of the member the message
  was intended for, and the severity of the problem causing the
  bounce.  The severity can be either hard or soft meaning either a
  fatal error occurred, or a transient error occurred.  When in doubt,
  a hard severity is used.

  If no member address can be extracted from the bounce, then the bounce
  is usually discarded.  Otherwise, each member is assigned a bounce
  score and every time we encounter a bounce from this member we
  increment the score.  Hard bounces increment by 1 while soft bounces
  increment by 0.5.  We only increment the bounce score once per day, so
  even if we receive ten hard bounces from a member per day, their score
  will increase by only 1 for that day.

  When a member's bounce score is greater than the bounce score
  threshold, the subscription is disabled.  Once disabled, the member
  will not receive any postings from the list until their membership is
  explicitly re-enabled (either by the list administrator or the
  user).  However, they will receive occasional reminders that their
  membership has been disabled, and these reminders will include
  information about how to re-enable their membership.

  You can control both the number of reminders the member will receive
  and the frequency with which these reminders are sent.

  There is one other important configuration variable; after a certain
  period of time -- during which no bounces from the member are received
  -- the bounce information is considered stale and discarded.  Thus by
  adjusting this value, and the score threshold, you can control how
  quickly bouncing members are disabled. You should tune both of these
  to the frequency and traffic volume of your list.

  Should Mailman perform automatic bounce processing?
  (Details for bounce_processing) Yes

  The maximum member bounce score before the member's subscription is
  disabled. This value can be a floating point number.
  (Details for bounce_score_threshold) 5.0

  The number of days after which a member's bounce information is
  discarded, if no new bounces have been received in the interim. This
  value must be an integer.
  (Edit bounce_info_stale_after) 7

  How many Your Membership Is Disabled warnings a disabled member
  should get before their address is removed from the mailing list.
  Set to 0 to immediately remove an address from the list once their
  bounce score exceeds the threshold. This value must be an integer.
  (Edit bounce_you_are_disabled_warnings) 3

  The number of days between sending the Your Membership Is Disabled warnings. 
This value must be an integer. 
  (Edit bounce_you_are_disabled_warnings_interval) 7

> Why not wait until there are, say, a dozen of them?  A small number of
> bounced messages means a temporary problem, which doesn't justify such
> drastic measures, IMO.

See the description for what Mailman is actually doing.  It says it
doesn't disable it on the first bounce.

> > Sure some addresses are only temporarily undeliverable.  That's why
> > Mailman uses rate limits.  Normally if there is a bounce or two it
> > doesn't do anything other than bounce those individual messages.  It
> > is only when there are many that something must be wrong and delivery
> > is suspended.
> 
> It does?  I certainly don't see that.  IME, a single bounced message
> causes a user's mail delivery to be disabled.  What did I miss?

I know my mail server has accidentally bounced all messages at times
and yet I was not bounced off the lists therefore it seems to be
operating as described.  It certainly did not bounce me off the lists
on the first bounce anyway.

Bob