[Mailman-Users] Wondering how long to send messages

[John W. Baxter]

On 8/27/2004 17:40, "Brad Knowles" <brad at stop.mail-abuse.org> wrote:

> At 6:37 PM -0400 2004-08-26, Mike wrote:
> 
>>  Wondering if anyone has a sense how long a message takes to send before I
>>  can make changes to the membership list. The concern is if I make changes to
>>  the subscriber list too quickly (remove them), then those folks may not get
>>  the message.
> 
> The answer is -- it depends.  A fast machine on a fast network
> with all recipients who are likewise on fast machines attached to
> fast networks, and with relatively few users, may be completely
> delivered in a few minutes.  But there could always be stragglers
> that are minutes, hours, or even days behind.

But it doesn't matter when the messages get delivered.  Removing an address
from the list does not reach out into the Internet and snatch back the
message that is on its way.

What matters is how the Mailman code gathers the addresses a particular
message is to be delivered to, and what it's doing while it sends out the
message to those addresses.

Does the code open the list once, obtain the addresses it needs (the
non-digest, not-no-mail, not duplicate filtered, etc) and then do its thing
without regard to the list object on disk, or does it keep peeking into the
object on disk while it's emitting messages.

Without looking at the code, my guess is it is more like the former than the
latter.  A quick look at the code suggests that's the case (the code which
sends out a message gets the recipients pre-cooked from an object).

In that case, the questions are
   is the list locked while the gathering takes place?
   if not, how long does the gathering take?

Once the addresses are gathered up (or the list is locked for gathering),
the list membership can be changed without worry...the worst that will
happen is that a bounce will come back related to an address not on the list
when the bounce comes.

If the code keeps peeking at the list object on disk, then what matters is
how long it takes to get the message to the SMTP server to which we submit
the messages.  That time can be read from the smtp log, and provides an
upper bound.  I doubt one needs to wait that long.  It's longer if Mailman
is VERPing.

  --John