Re: Configure sendmail to bypass user lookup and...

In article <1181564988.967465.52110@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
walter.wade.jr@xxxxxxxxx wrote:

I'm not at all familiar with sendmail, so please forgive me if any of
what I say is confusing.

My site is preparing for a sendmail to Exchange migration.

It sounds like you've made up your mind, but you should be aware that
this is a move that many have come to regret. Exposing Exchange to the
Internet is a very risky proposition.


What we
are hoping to do is the following:

1) Change MX record to point to Exchange Server so that it becomes the
main mail server for our site.
2) Configure Exchange to forward e-mails to a user's mailbox on the
legacy UNIX mail server.
3) Have a user who is configured to use the legacy UNIX server as the
pop3/smtp server to be able to send e-mail to an Exchange Server
mailbox using a naming convention of first.last@xxxxxxxxxxx The UNIX
mail server uses legacy@xxxxxxxxxx as it's naming convention.

The only issues we've encountered is with item #3.

3a) Using the UNIX pop3/smtp server, when a user tries to send an
email to first.last@xxxxxxxxxx, the UNIX mail server refuses it
because it says user unknown since it doesn't know who first.last is.
To get around that, we configured the Exchange mailbox to use
legacy@xxxxxxxxxx as the default address. That seems to work as the
UNIX mail server does the username lookup, accepts the e-mail, and
"sends" it to its destination. However, we run into our next issue...

3b) The e-mail sent to legacy@xxxxxxxxxx never seems to leave the UNIX
server (even though the MX record is pointing to the Exchange Server)
and just sends it to the local mailbox that exists on the UNIX server.

So, for my questions:

1) How can we configure the UNIX server to bypass the username lookup
so that we send e-mail to first.last@xxxxxxxxxx, instead of
legacy@xxxxxxxxxx?

2) How can we configure the UNIX server to not look at itself as
domain.com, so that it'll send any e-mail to domain.com to the
Exchange Server?

You're going to need to learn a bit about Sendmail configuration. The
first place to start reading is the README file in the cf directory of
the sendmail source distribution. It explains all of your options (which
are extensive) and how to build the master configuration file,
sendmnail.cf, which normally is in the /etc/mail directory. That build
process (at least in modern times) almost always involves creating an
input file (sendmail.mc, typically) and using the "Build" script in the
cf/cf diretory of the sendmail source tree to generate sendmail.cf. If
your existing config was built normally with a recent version of
Sendmail, the entire sendmail.mc source should be at the end of your
sendmail.cf, as comments.

Exactly how to do what you want is going to depend on some local details
that you have not specified. Depending on your existing config, you
might be able to keep your existing sendmail.cf and just modify external
files that it uses, or you may need to completely redo sendmail.cf in
order to get behavior you like. In looking at your configuration, you
will want to pay attention to whether you use an external file to list
your local hostnames (specified by a 'Fw' line in sendmail.cf) or
whether your local name is only specified in sendmail.cf (only a 'Cw'
line) and so on... I suspect that you will want either to use the "User
DB" feature or perhaps a combination of virtual users and a "generics"
mapping table, but maybe you could get away with aliases, .forward
files, and a luser relay.

And getting back to my first point: you COULD keep Sendmail as your
external face and use its features to selectively relay mail in to
Exchange, rather than have Exchange on the outside and Sendmail sitting
behind it. That might well be simpler to migrate to, and since a major
function of external MTA's these days is usually spam control, it
usually is a better option to keep something highly flexible like
Sendmail as your external face.

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

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