Duplicates

[Joel Newkirk]

On Wed, 10 Sep 2008 02:57:27 -0700 (PDT), Yann Neveu
<yann_openmoko at gabuzomeu.fr> wrote:
> 
> Ok so it does affect non gmail users too...
> I've posted precedent message using my ISP relayhost (free.fr) and
> according
> to the mail headers, the relay host sent 3 times the mail to
> sita.openmoko.org.
> I suppose sita replied the mail was not accepted, try later bla bla bla
> but
> finally dit it. So the server resent it 10 minutes later and 20 minutes
> later.
> 
> Is there misconfigured greylisting on list?
> 
> I'll try later with my own stmp to see the sita's responses cheking the
> logs.

I tested it out pretty thoroughly (for being 'outside' the mailserver
itself) and posted a long description on Sep1 "Re: Duped Messages (OffTopic
but important to lists.openmoko.org operations)" on the Community list. 
The problem is that the mailserver sita.openmoko.org is sometimes taking a
VERY long time to send the '250 OK' response after receiving a message, and
the sending mailservers are giving up waiting and try to redeliver. 
Strictly speaking, they are supposed to wait for that response for up to 10
minutes before considering the delivery failed, but I consider that an
antiquated spec, deriving from the SMTP RFC all the way back in 1982.  Very
few mailservers will actually sit and wait out the 10 minutes before giving
up.  In my telnet-to-smtp tests I gave up after 4+ minutes the 20% or so of
attempts that it did this - the other 80% or so it responded with the '250
OK' almost immediately.

It's likely that some virus or spam filtering measures on the receiving
server (sita.openmoko.org) are getting hung up sometimes - especially since
it doesn't always happen, even to the same sender from the same sending
server.  It's counter-intuitive, but the fix is often to limit the server
to fewer simultaneous inbound connections, which has the effect of using
less resources on the server.  (sending servers will automatically retry,
as we've seen)

j