Your best bet is really to configure Exchange to handle *all* your mail. If
you just wanted shared calendaring/contacts, there were cheaper options.
Using Outlook 2000 and earlier versions, you cannot use Internet Mail and
Exchange in the same profile reliably - it is not a supported configuration
and will usually result in "no transport provider available" messages. You
could upgrade to Outlook 2002/Office XP, but really, there is no
disadvantage to hosting your own mail and ditching the POP mail, and a
gazillion advantages...
You are sorta defeating the point of a centralized server by relying on
Outlook to handle Internet mail. Hosting your own domain's mail will be a
lot easier, mail will be faster, you'll be able to use OWA and Out of
Office, you can easily assign multiple addresses to each user, can use
mail-enabled public folders, publicly addressable distribution lists/groups,
and can scan all inbound/outbound mail for viruses using Exchange AV
software on the server.
See MSKB 245446 for info on the
No transport provider error message, and a statement that this is not a
supported configuration.
See
http://www.msexchange.org/tutorials/MF002.html for instructions on how
to get Exchange 2000 to receive Internet mail sent via SMTP, the way it's
meant to do. For Exchange 5.5, see
http://www.exchangeadmin.com/Articles/Index.cfm?ArticleID=15729
You can do this even with dialup/ISDN (get an ISP who supports ETRN) .
If you have broadband but with a dynamic IP (such as a cable modem/ADSL
account):
You can use a dynamic DNS host such as
www.dyndns.org - you set up an
account, such as yourcompany.dnsalias.com, and whomever hosts your public
DNS should set your primary MX record to point to yourcompany.dnsalias.com.
Open up port 25 inbound in your firewall or router, direct all traffic to
your internal IP for the Exchange server.
You run a service on your server (software available for download from the
dyndns website) and set it up to update dyndns with your current dynamic
IP.