OT Routing problem MS sendmail and exchange {Scanned by HJMS}

Furnish, Trever G TGFurnish at HERFF-JONES.COM
Tue Oct 14 15:00:09 IST 2003

So during your transition process you are trying to host the same domain on
two servers, each of which only has some of the valid users for that domain?
That won't work -- or at least it's a very odd way of doing things.

And maintaining a list of which users have been moved and which ones haven't
is "too much administration"?  If maintaining a list of users is too much
work for you, then hire an email administrator and stop trying to do it
yourself.  Successfully migrating from one mail system to another is a
process that should be undertaken by someone willing to be extremely careful
and extremely thorough.

But in the spirit of being helpful, I'll offer this suggestion: give your
exchange server its own subdomain and use sendmail's virtusertable to
forward mail to the users migrated to exchange.

In greater detail:

Let's imagine that your original domain is foo.com, and that your sendmail
server is sm.foo.com and your exchange server is ex.foo.com.

You originally had MX records that looked like this:
foo.com.        IN MX   10 sm.foo.com.

Given that starting point, what you should have done was to assign a
subdomain to the exchange server before moving your users there.  For
example, you could assign mail.foo.com to the exchange server:
mail.foo.com.   IN MX   10 ex.foo.com.

Then, when you create a mailbox on the exchange server, you assign BOTH the
user's original @foo.com address AND a new @mail.foo.com address.  Exchange
will happily accept multiple smtp addresses for the same mailbox.  Be sure
that you set the @foo.com address as the mailbox's primary address -
otherwise when the user sends email it will go out as something else.  For
example, Joe Shmoe's new mailbox on the exchange server would have two smtp
addresses (as well as all the other addresses exchange creates):
joe.shmoe at foo.com   <-- set as primary
joe.shmoe at mail.foo.com

Now, on your sendmail system all you have to do is forward users as you move
them.  You can do this with aliases or with the virtuser table, whichever is
appropriate for your set-up.  If you're using aliases, then on the sendmail
server you would have an alias of:
joe.shmoe:      joe.shmoe at mail.foo.com

After moving a user mailbox you should forward and clear the user mail spool
on the sendmail server - then you will be able to spot any email still being
delivered to the user's spool.  If there is still mail flowing into the
spool of a forwarded user, then he has an address that you have missed -
just forward that one as well.

When you have moved *all* users off of the sendmail server, then you can
take foo.com out of the sendmail server's list of local domain names
(/etc/mail/local-host-names or /etc/mail/sendmail.cw) and add a RELAY line
to the sendmail access file for the domain (assuming you still want to use
the sendmail server as a relay for it).  Then you also need to update DNS to
direct email to the exchange server directly, so you might end up with:
foo.com.        IN MX   10 sm.foo.com.
foo.com.        IN MX   5 ex.foo.com.

If you intend to use the sendmail system as a mailscanner gateway for the
exchange server, then you also need to prevent email from flowing directly
to the exchange server without first hitting the sendmail server.  If your
exchange server is on windows server 2003 you can probably just reject
connections to port 25 from everything EXCEPT sm.foo.com.  If you have an
earlier version of windows then you probably want to use sendmail's
mailertable or smarthost feature instead.


> -----Original Message-----
> From: Carl Boberg [mailto:carl.boberg at NRM.SE]
> Sent: Tuesday, October 14, 2003 8:32 AM
> Subject: OT Routing problem MS sendmail and exchange {Scanned by HJMS}
> Hi,
> I have been looking everywhere fo a solution to this.
> Using Malscanner a mailgateway (lowest MX)
> In the DMZ i have a sendmail sever my users connetct to for 
> I now have a new Exchange server and new users on this one 
> and migrating old
> users
> slowly from the sendmail to the exchange.
> MS smtpGW scans all mail comming in an the sends all mail to the new
> Exchange server.
> All email the exchange server cant resolve it sends to the 
> old sendmail
> server (even @domain.com addresses)
> But the sendmail will only deliver @domain.com if there exist 
> a local user.
> I need to figure out how to make sendmail deliver local 
> addresses and those
> @domain.com adresses it doesnt have localy sould be sent to 
> the exchange
> server?
> How to solve when a local domain (@domain.com) address has 
> been moved???
> I could maintain the aliasses file on the old server but that 
> is way too
> much administration.
> Also can I make the Mailscanner Mailgateway relay mail to my internal
> mailservers on a trial error basis?
> Incomming mail to @domain.com first try internalmailserver1.domain.com
> if NDR (non delivery reply) then try internalmailserver2.domain.com
> Sorry if im unclear or messy in my description.
> Thanks for any help in advance.
> Bets regards
> --------------------------------
> Carl Boberg
> System & Network Administrator
> Swedish Museum of Naturalhistory
> Frescativägen 40
> 104 05 Stockholm
> Sweden
> Tel nr: 08-5195 5116
> Mobile: 0701-82 4055
> E-mail: carl.boberg at nrm.se
> --------------------------------

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