I don't know if this is the right group to post to, but I am at a loss
to explain what is happening and how to fix it.

For about 2 years, my company has had email, web hosting, ftp and
domain services with a provider called iPowerWeb. About a year ago we
installed a local server, and in August we transitioned our email to
the local server, via an MX record update, due to strange problems with
the email services. Everything seemed fine at the time, but we started
to notice email wasn't being delivered. The senders didn't get an
error, but we never got the email. Our IT contractor mentioned that
maybe it was being mis-delivered and was on the old iPower server. Sure
enough, everything was there.

I would really like to know several things.
1. What might be causing this?
2. How can I make sure that it doesn't happen again?
3. Is there a local redundancy system that can be incorporated into our
Windows SBS2003 server setup that will keep this from happening?

I don't know much about this type of thing and I don't have the
experience to delve deeply into the workings of the systems, I am more
looking for things to suggest to the IT contractor and to the hosting
provider.

Thanks!