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We are running Exchange 2003 Standard. While IMAP or OWA access is easy to provide for people who are never on site, we have difficulty administering access for those staff who have a laptop, and for example, work at home or on the road two days a week.

Is it possible to set up their Outlook client to connect directly to the Exchange when they are on-site, and swith co IMAP when they are off-site? How do you handle this kind of scenario?

I know Ex/Outlook 2K7 have provisions for this (using ActiveSync I think), but I was wondering what the best way to handle this using Ex2K3 was? Currently our only option is to limit them to OWA or to give them VPN access, neither of which are preferable.



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You do NOT want to do IMAP and MAPI access. That would be a sucky user experience, especially with pre-2007 versions of Outlook. sysadmin1138 has it right all the way. –  Evan Anderson Jun 18 '09 at 15:04

5 Answers 5

What you're looking for is "RPC over HTTP". We did this with Exchange 2003, and it worked well. The one caveat we ran into won't be problem for you, it seems you have to have unrestricted access to the Exchange servers to set it up; this was a problem for home desktop users but for a mobile workforce that's in the office at least once a week isn't a problem. That'll allow them to use the same access method (RPC over HTTP) both at home and in the office.

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+1 - RPC over HTTP, AKA "Outlook Anywhere", is exactly what the poster needs (and is, very, very handy). –  Evan Anderson Jun 18 '09 at 15:03
+1 I did this on the last company I worked and it was great. RCP over HTTP is what you're looking for –  Hondalex Jun 18 '09 at 18:51

Our "resolution" to this dilemma ... (Exch 2003, Outlook 2003):

1- ActiveSync is widely used here. We have a bunch of iPhone users (including myself), and a number of other smartphones.

2- For company laptops we setup Outlook in "cached mode", and it connects to Exchange when the PC is connected to the network via VPN. When not connected, they can still work in offline mode.

3- We do not allow home (i.e. non-company) PCs to connect to the network or to connect Outlook to Exchange. If we haven't given you a laptop, then OWA or ActiveSync have to do. We don't want someone's mail in a PST/OST on a computer that we don't own.

4- We tried to setup RPC over HTTP two years ago and failed. We haven't tried since the "Outlook Anywhere" concept arrived. We are going to look again this summer. For security reasons, it won't be activated unless we can restrict the connection to domain computers.

To respond to your questions:

  • You could open IMAP to the Exchange server from the internet, and have an Exchange account and an IMAP account configured in Outlook. I would not do that .. the client configuration will be difficult to manage, the users will struggle, and although I don't know for sure it smells insecure.

  • If you don't want VPN and must have Outlook then setup RPC over HTTP. Those who use it love it, and apparently it is quite secure. We never got it working, but we have an ISA proxy gateway, which was "best practice" when we implemented but has since fallen from favor.

  • If possible, I would not allow non-company computers access to the network or to Exchange via Outlook, for the reason I noted above.

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Another vote for Outlook Anywhere. Set up Outlook to work in cached mode and Outlook will seamlessly work when on the LAN and when on the road connecting through the Internet. If you're using SBS just run the Internet connection wizard to enable it. If you're using pukka Exchange 2003 it can be a bugger to set up. See for my walkthrough.


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We use an SSL-VPN product from Sonicwall to provide VPN access to the LAN and then run the standard Outlook client.

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I would give them Outlook Cached mode for when they are out of the office.

  1. VPN will be the primay way to dial in and they get full outlook functions. Just tell them it will be slower.

  2. Put an internet short cut on their desktop for OWA, tell them if the VPN is not working, or Outlook is just too slow, then use the OWA link.

I have a place setup that doesn't even do number 1, they know when not in the office they are on OWA or a mobile device if they have been issued one.

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