[zorba]

Hi, I am new to Exchange (having up till now run our Outlook email clients as standalone clients collecting
to .PST files on a LAN file server, collecting via POP3 from our email server hosted by a commercial
provider - Xilo).

5 days ago (on Monday 12th Nov) I had a networking company come in and set up Exchange server for us.
Exchange mailboxes replaced our .PST files (with the .PST data migrated into the Exchange mailboxes).

Initially, just for continuity and to avoid throwing everything up in the air together, we continued to
collect mail into Exchange via POP3 (using the same mailboxes provided by Xilo our hosts).

Then on Thursday (15th Nov) we finally "grew up" and setup Exchange to run as a collecting mailserver in
its own right (by configuring Exchange, and by contacting our hosts Xilo, giving them our Exchange server's external IP address, and asking them to re-route mail directly to us - via creating an MX record in their DNS I believe).

(Q1) On Thursday, did we go from collecting mail via POP3 to collecting via IMAP ?

(Q2) All along i.e. from Monday, have we been SENDING mail using SMTP ? (and therefore bypassing our hosting provider's mailserver)

Today (Friday) we noticed that mail we sent to was not being received. Our network engineers told us we needed a Reverse DNS record created (rDNS), and to contact our ISP. Which we did, and within 30mins this was implemented - albeit with the proviso it would take 24-48 hours to propagate through the internet.

It was explained to me that some external mailservers don't like mail "from mailservers that don't have a
Reverse DNS setup", yahoo being a prime example. As you can imagine, I am aggrieved that someone didn't
think of this sooner, as potentially we could have sent other mail out, that will not be accepted. Anyhow,
no use crying over spilt milk, but this has left me with questions...

(Q3) Does this mean that potentially any mail we sent out since Monday (when the Exchange server was
switched on) could have been rejected by receiving mailservers, because of the lack of an reverse DNS ?
If so, we would want to confirm by other means (e.g. phone) that email has arrived, or send again, and hope
that the reverse DNS fix will enable mailservers to receive it this time.

(Q4) Have I got this correct - since our domain is still hosted by Xilo, our mailserver there is a
"virtual" mailserver, and the record in their DNS points back to our own Exchange servers IP address ?
Therefore our domain name will resolve to an address with Xilo ?
However a reverse DNS lookup, shows that our local IP address is associated with our domain name ?
And if these last 2x statements are true, with a conflict of IP addresses - does this mean we will get
problems with mailservers, websites etc. rejecting our mail etc. because they think we are spammers ?

(Q5) I realise our setup is quite complex, and I'm terrified there might be other problems a la MISSING
REVERSE DNS lurking out there. As you can imagine, given the fact that they were reactive not proactive re. the MISSING REVERSE DNS I am losing confidence in my network engineers to do the theoretical exercise and predict possible future problems. Can anyone out there see anything ? Or point me in the direction or a
resource (flesh-and-blood person, corporate body, or information source) who will be able to look at our
setup and give some definitive (or closer to definitive than I've been getting so far!) answers, on how
robust our setup is and what we might need to do to pre-empt any future problems ?

I'm not sure if its relevant, but our domain is registered by a different third party, but the nameservers
all point to Xilo (our hosts) nameservers.

Please help me out of this quagmire!

z.