dns with multiple mail servers

I am working on a project for a local community college to implement a
mail system for the 12,000 students that attend the college. I am
planning on using linux, with sendmail or postfix. I have one thing I
haven't figured out yet. The staff already has a email system for the
staff and faculty (probably in Microsoft Exchange) up and running, but
I want to add another server just for the students at the same domain
that the school is already using for faculty and staff. Without using
a subdomain, how can the DNS server route the mail to the correct
server on the network if the recipients address contain the same high
level domain?

Thanks for your time,

William Jimenez

Re: dns with multiple mail servers

wjimenez5271@gmail.com wrote:
> I am working on a project for a local community college to implement a
> mail system for the 12,000 students that attend the college. I am
> planning on using linux, with sendmail or postfix. I have one thing I
> haven't figured out yet. The staff already has a email system for the
> staff and faculty (probably in Microsoft Exchange) up and running, but
> I want to add another server just for the students at the same domain
> that the school is already using for faculty and staff. Without using
> a subdomain, how can the DNS server route the mail to the correct
> server on the network if the recipients address contain the same high
> level domain?

The DNS won't help here, as it can't know what the one who makes the
DNS-lookup intend to do.

You would need to setup a front server which forwards the mail to the
staff-mail-server if the mail is to one of the staff and forward the mail to
the student-mail-server if the mail is to a student. You could also make some
first line spam filtering here too.

--

//Aho

Re: dns with multiple mail servers

In article <1192952452.198512.274880@i13g2000prf.googlegroups.com>,
wjimenez5271@gmail.com wrote:

> I am working on a project for a local community college to implement a
> mail system for the 12,000 students that attend the college. I am
> planning on using linux, with sendmail or postfix. I have one thing I
> haven't figured out yet. The staff already has a email system for the
> staff and faculty (probably in Microsoft Exchange) up and running, but
> I want to add another server just for the students at the same domain
> that the school is already using for faculty and staff. Without using
> a subdomain, how can the DNS server route the mail to the correct
> server on the network if the recipients address contain the same high
> level domain?

Magic and telepathy.

If you are not able to integrate magic and telepathy (you will need
both) with your DNS services, the only way to make DNS discriminate
between queries made for the purpose of delivering two different logical
sets of email addresses is to put those addresses in two different
domains. DNS does not route mail. DNS does not deal with email
addresses, it deals with domain names.

There are multiple ways to configure Sendmail (and most other MTA's) to
act as a public-facing mail exchanger for a domain with addresses that
are delivered in diverse places.

--
Now where did I hide that website...

Re: dns with multiple mail servers

wjimenez5271@gmail.com wrote in news:1192952452.198512.274880
@i13g2000prf.googlegroups.com:

> I am working on a project for a local community college to implement a
> mail system for the 12,000 students that attend the college. I am
> planning on using linux, with sendmail or postfix. I have one thing I
> haven't figured out yet. The staff already has a email system for the
> staff and faculty (probably in Microsoft Exchange) up and running, but
> I want to add another server just for the students at the same domain
> that the school is already using for faculty and staff. Without using
> a subdomain, how can the DNS server route the mail to the correct
> server on the network if the recipients address contain the same high
> level domain?
>
> Thanks for your time,
>
> William Jimenez
>


If you don't want to have a sub-domain for the student emails then I
suggest you learn as much about the existing mail system as possible
since you will want the faculty/staff to send email to the students as
seemlessly as possible and depending on what they have setup this may
involve some work. If you setup a front end server running say LDAP mail
routing (see sendmail docs) you might want all mail sent to it even from
faculty/staff to allow it do do its job. So look into LDAP routing; DNS
cannot help you here.

Andy

Re: dns with multiple mail servers

On Oct 21, 3:40 am, wjimenez5...@gmail.com wrote:
> I am working on a project for a local community college to implement a
> mail system for the 12,000 students that attend the college. I am
> planning on using linux, with sendmail or postfix. I have one thing I
> haven't figured out yet. The staff already has a email system for the
> staff and faculty (probably in Microsoft Exchange) up and running, but
> I want to add another server just for the students at the same domain
> that the school is already using for faculty and staff. Without using
> a subdomain, how can the DNS server route the mail to the correct
> server on the network if the recipients address contain the same high
> level domain?
>
> Thanks for your time,
>
> William Jimenez

You would need to put the students in a different domain, such as
student.schoolname.edu (or schoolnickname.edu) but before you dismiss
that possibility, consider how much simpler your life will be if you
do so. You won't be responsible for forwarding staff mail from your
server to the staff server, nor will your server be blamed for every
lost incoming message. You won't need cooperation from the maintainer
of the staff server either. That cooperation is important, since you
will need to be informed of every legitimate email address on the
staff server, so that your server will know if any particular message
should be accepted. Also, you can easily have different rules for
maximum message size or spam filtering which is more difficult within
a single domain..

I know that few schools do this, but perhaps they have plenty of
resources, or got started before the problems became apparent? I
notice that virtually all schools separate alumni accounts this way.
You might want to post on the Higher Education Email Administration
mailing list, which is at

http://listserv.nd.edu/cgi-bin/wa?A0=hied-emailadmin

Maybe people there will respond "I wish I had done that", or "There is
a reason it isn't done." Either way it is likely to be more
informative than a posting here.

Daniel Feenberg