how isp can hold mail temporary ?

Hi,

If the setup like this ..
ISP --> server1(abc.com)
-->server2 (xyz.com)
-->server3(sdf.com)

now both the server and isp running qmail . if the link between
server
and client broken than the ISP will hold the mail temporary and when
the link is up the isp will forward the mail . Is it possible ...how
to do that ?
....is there is any specific name / keyword (for google search for
this type of situation ?

Please help . Thanks .



learnq

On Jul 1, 1:33*am, learnq <lea...@gmail.com> wrote:
> Hi,
>
> If the setup like this ..
> ISP *--> server1(abc.com)
> * * * *-->server2 (xyz.com)
> * * * *-->server3(sdf.com)
>
> now both the server and isp running qmail . if the link between
> server
> and client broken than the ISP will hold the mail temporary and when
> the link is up the isp will forward the mail . Is it possible ...how
> to do that ?
> ...is there is any specific name / keyword (for google search for
> this type of situation ?
>
> Please help . Thanks .

Yes, this is exactly what mail servers do. Google "mail queue".

DS

soorry ..my mistake ...it is not client ...

My question is ...if the link between ISP and Servers (1/2/3) is
down ... than ISP holds mail
for the domains that is configured in the servers ...how it is
possible ??
as the domain is configured in the server ??


learnq wrote:
> Hi,
>
> If the setup like this ..
> ISP --> server1(abc.com)
> -->server2 (xyz.com)
> -->server3(sdf.com)
>
> now both the server and isp running qmail . if the link between
> server
> and client broken than the ISP will hold the mail temporary and when
> the link is up the isp will forward the mail . Is it possible ...how
> to do that ?
> ...is there is any specific name / keyword (for google search for
> this type of situation ?
>
> Please help . Thanks .

On Jul 2, 1:20*pm, learnq <lea...@gmail.com> wrote:
> soorry ..my mistake ...it is not client ...

Right, mail servers have mail queues.

> My question is ...if the link between ISP and Servers (1/2/3) is
> down ... than ISP holds mail
> for the domains that is configured in the servers ...how it is
> possible ??
> as the domain is configured in the server ??

Typical ISP mail servers have to hold mail even for unconfigured
domains. If a customer sends them mail to deliver, and the destination
mail server can't be reached, they hold the mail in a "send queue".
They then retry the mail periodically.

A typical setup will send the originator of the mail a message after
two to four hours (called a 'temporary failure' message). They will
typically give up after two days, and send the originator a permanent
failure message.

DS

On Thu, 03 Jul 2008 12:56:18 -0700, David Schwartz wrote:

> They will
> typically give up after two days, and send the originator a permanent
> failure message.

This varies. I've seen AOL use 12 hours, with is ridiculously short.
Back in the day, five days was about the longest I'd seen.

- Andrew

On Jul 4, 5:56*am, David Schwartz <dav...@webmaster.com> wrote:
> On Jul 2, 1:20*pm,learnq<lea...@gmail.com> wrote:
>
> > soorry ..my mistake ...it is not client ...
>
> Right, mail servers have mail queues.
>
> > My question is ...if the link between ISP and Servers (1/2/3) is
> > down ... than ISP holds mail
> > for the domains that is configured in the servers ...how it is
> > possible ??
> > as the domain is configured in the server ??
>
> Typical ISP mail servers have to hold mail even for unconfigured
> domains. If a customer sends them mail to deliver, and the destination
> mail server can't be reached, they hold the mail in a "send queue".
> They then retry the mail periodically.
>
> A typical setup will send the originator of the mail a message after
> two to four hours (called a 'temporary failure' message). They will
> typically give up after two days, and send the originator a permanent
> failure message.
>
> DS

How does " ISP mail servers have to hold mail even for unconfigured
domains." ? can you link some tutorial / keyword that explans
how to configure the " ISP end " to do that ?

On Jul 20, 9:06*pm, learnq <lea...@gmail.com> wrote:
> On Jul 4, 5:56*am, David Schwartz <dav...@webmaster.com> wrote:
>
>
>
> > On Jul 2, 1:20*pm,learnq<lea...@gmail.com> wrote:
>
> > > soorry ..my mistake ...it is not client ...
>
> > Right, mail servers have mail queues.
>
> > > My question is ...if the link between ISP and Servers (1/2/3) is
> > > down ... than ISP holds mail
> > > for the domains that is configured in the servers ...how it is
> > > possible ??
> > > as the domain is configured in the server ??
>
> > Typical ISP mail servers have to hold mail even for unconfigured
> > domains. If a customer sends them mail to deliver, and the destination
> > mail server can't be reached, they hold the mail in a "send queue".
> > They then retry the mail periodically.
>
> > A typical setup will send the originator of the mail a message after
> > two to four hours (called a 'temporary failure' message). They will
> > typically give up after two days, and send the originator a permanent
> > failure message.
>
> > DS
>
> How does " ISP mail servers have to hold mail even for unconfigured
> domains." ? can you link some tutorial / keyword that explans
> how to configure the " ISP end " to do that ?

I understand that if I change the MX preference than.... if my server
is down ....
it will go to seecond prefer MX (ISP).
So do I also need to configute ISP to hold mail for that domain&its
users ??
mailbox for every user configured in ISP&the server is not
logical !!!
What 'concept' I am missing ??

On Jul 20, 4:06*am, learnq <lea...@gmail.com> wrote:

> How does " ISP mail servers have to hold mail even for unconfigured
> domains." ? can you link some tutorial / keyword that explans
> how to configure the " ISP end " to do that ?

It should be automatic. I have never heard of a mail server that
didn't have automatic built in support for a mail queue. You always
have to hold onto outbound mail until you manage to deliver it.

There is almost certainly nothing special you have to do. The
'sendmail' program, for example, normally stores outbound mail in
'/var/spool/mqueue'. For each outbound message, there are two files.
One contains the actual mail data, the other contains control
information such as when the last attempt to send the message was
made.

DS

On Jul 20, 4:24*am, learnq <lea...@gmail.com> wrote:

> I understand that if I change the MX preference than.... if my server
> is down ....
> *it will go to seecond prefer MX (ISP).
> So do I also need to configute ISP to hold mail for that *domain&its
> users *??
> mailbox for every user configured in ISP&the server is not
> logical !!!
> What 'concept' *I am missing ??

What you're missing is that this is not mail stored in a mailbox, it's
mail stored in a queue.

The trucks that carry mail carry mail *to* every address on the
planet. But they don't have a special 'mailbox' for every possible
destination address. They just pile all the mail together and then
look at each piece to see where it needs to go next.

DS

David Schwartz <(E-Mail Removed)> wrote:
> On Jul 20, 4:06*am, learnq <lea...@gmail.com> wrote:
>
>> How does " ISP mail servers have to hold mail even for unconfigured
>> domains." ? can you link some tutorial / keyword that explans
>> how to configure the " ISP end " to do that ?
>
> It should be automatic. I have never heard of a mail server that
> didn't have automatic built in support for a mail queue. You always
> have to hold onto outbound mail until you manage to deliver it.
>
> There is almost certainly nothing special you have to do. The
> 'sendmail' program, for example, normally stores outbound mail in
> '/var/spool/mqueue'. For each outbound message, there are two files.
> One contains the actual mail data, the other contains control
> information such as when the last attempt to send the message was
> made.

The advice in this thread has been generally true however thanks to the
spammers there is now an extra wrinkle. Each MX for a domain needs to
be able to verify that a particular address in that domain is legitimate
before accepting the email. If it doesn't do this it will become a
source of backscatter spam and end up on an RBL before long. This is
why there are so few backups MXs now - no longer is it a 5 minute job to
set one up. One popular option for those that do run a backup MX is to
have the MXs do ldap lookups to verify users.

Cheers,

Rob