Merging companies......need help

[Kevin Darcy]

dave.hampel at cominco.com wrote:

> Hi:
>
> We are currently merging with another company and the result is a
> domain with the two names combined. Example: companya and companyb.
> Resulting in the domain  companyacompanyb.
>
> In companya we have a fully working DNS system with the MX record
> pointing to a single mail server.
> In companyb they have the same thing.
>
> How do I get DNS to advertise that mailboxes for companya can be found
> on companya's mail server and mailboxes for companyb can be found on
> companyb's mail server using an MX record for companyacompanyb?
>
> That is, if we put aliases on all our existing mailboxes on both
> servers as user at companyacompanyb.com, how do I add an MX record that
> encourages outside mail servers to check BOTH mail servers for the
> valid recipient?
>
> Or am I out to lunch????

As it happens, I know a thing or two about rearchitecting SMTP following
a merger... :-)

You're out to lunch. DNS doesn't resolve *mailboxes*, it resolves mail
*exchangers*. You should have a server (or set of servers) that accepts
mail for companyacompanyb.com and either accepts the message directly or
forwards it to another server, depending on whether it's a "companya" or
a "companyb" user. Watch for name collisions, though: if there's a
john.smith at companya.com and a john.smith at companyb.com, you'll have to
have some way of deciding which of them, if any, gets to be
john.smith at companyacompanyb.com (fortunately in our case we had
mutually-exclusive mailbox-naming conventions).


- Kevin