On Thu, 25 Sep 2008, Pieter V. wrote:
> Same here, for whoever may be wondering.
>
> On Thu, Sep 25, 2008 at 9:51 PM, Cecil Coupe <[EMAIL PROTECTED]> wrote:
>
> > On Fri, 2008-09-26 at 00:21 -0400, Seth Thomas Rasmussen wrote:
> > > I dunno about you guys, but I've had a handful or so of messages in
> > > various threads arriving out of order for me lately. The first message
[...]
> >
> > That's been happening to me for several weeks. Not a huge problem on a
> > low volume mailing list, yet.
It's been happening to me for about 18 years, probably more.
I've not entirely understood this, given that TCP (rather than UDP)
delivers things in order and reliably. I think what is happening is
this:
Any mail server as a destination has several hosts that can receive
mail for it. These are in the DNS (domain name service) as MX (mail
exchange) records. There may be many reasons why any one of them is
not accepting mail at a given time, but if several are tried, then
the messages will be queued on different machines. Then their
delivery times will be essentially independent. Also, which MX
record is tried first, is, IIRC, usually randomized a bit, subject
to prioritied defined in the DNS.
On any given machine queueing mail for transmission, the mail will be
held until a retry time, or until that gets reset by something, such as
the server connecting in the other direction. Messages in the retry
queue may be retried after the messages that have not been tried for
that host are sent. I think that is pretty much up to the designer
of the Mail Transfer Agent (the delivery program).
It might be that if you look at the headers, and I've not done this,
that you can see for 2 out-of-sequence messages how they were routed.
Hugh
