Re: Failover to different hosted exchange

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Here is the problem. If you have 2 providers hosting mailboxes, each of
them having MX records for the same domain, even if you set one up with a
higher preference, you are guaranteed to receive mail on both MX records,
and it may not just be a trickle.. The other problem associated with this
is that if the secondary is configured with the same e-mail addresses, you
will be hard-pressed to find a way to make it send ALL mail to the primary,
and not deliver any of it to the local mailboxes. What you'd probably have
to do is make it so that the secondary would not receive mail (i.e. shut off
the SMTP service) until you want it to. This would prevent delivery of mail
to that location while the primary is up. If the primary goes down, then
you could enable SMTP on the secondary and allow mail to be delivered. The
other problem associated with this is that once your primary comes back up,
how are you going to get mail from the secondary back into the primary?
Also, how do you deal with adding/deleting users? Will your user creation
process include setting up user accounts in both locations? What if you
forget to add/delete on one side or the other?

It is typically very cost-ineffective to host both a primary and a DR set of
hardware. My company provides a solution (both an "emergency" messaging
solution, and a full-blown replication solution). I'm not trying to sell
you on our product, but I think you'd find it to be a fairly cost-effective
solution. Plus, we offer 60-second failover (for our EMS product) and we
re-import mail back into Exchange after the primary is back online. We also
address the user account issues by synchronizing with your primary AD
environment.

Whether you check us out or not doesn't matter to me - I just wanted to
bring up some of the potential pitfalls of the what you are considering.

http://www.messageone.com is our website.

--
Ben Winzenz
Exchange MVP
MessageOne


<dustbort@xxxxxxxxx> wrote in message
news:1125503470.661387.10890@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Our company uses hosted exchange. We recently had a situation where
> our provider was down for an entire week (our entire dedicated cluster
> was down; we are leaving them soon), during which we could not send or
> receive emails (and we also lost some email that was sent to us during
> that time). We are looking for an intermediate solution as we decide
> whether to bring Exchange in house. It will be at least a quarter
> until we can do that. We are afraid that if we switch completely to
> another Exchange host, that they may be no better than our current one
> (which is supposed to be relatively good), so we are trying to get some
>
> kind of redundancy.
>
>
> What we are considering doing is setting up a parallel set of mailboxes
>
> (for each mailbox at primary host, there exists a mailbox at secondary
> host with an identical set of accepted email addresses) with a
> completely separate provider, and adding an MX record to that host with
>
> a higher preference number. This way, when the primary Exchange host
> is down, the mail will be sent to the secondary host.
>
>
> My question deals with how Exchange on the secondary host will handle
> the emails. If there is an email destined for x...@xxxxxxxxxx, and the
>
> primary is down, assuming there is a mailbox at the second host that is
>
> also set to accept mail sent to x...@xxxxxxxxxx, would the mail be
> delivered to that mailbox and/or would it be queued for delivery to the
>
> primary host?
>
>
> I know this setup could result in some mail trickling into the
> secondary host from time to time, but this is a temporary solution, so
> that would be aceptable. Our requirements during the outage are simply
> to be able to send and receive emails at the same email address with as
>
> little overhead at the time of failover as possible. We do not want
> mail to be simply queued and untouchable during the outage. Also, we
> would not worry about pointing user's outlook clients to the secondary
> mailboxes; we would just use OWA through the secondary host.
>
>
> Sorry if this question sounds familiar, but most of the other posts are
>
> for in house exchange servers. These are separate hosts, so we cannot
> cluster.
>


.

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